Early years in Yamagata

In 1907 Yamagata, seven-year-old Oshin is sent off by her father to work as a babysitter to support her sharecropper family. Her boss is a timber trader, and despite the physical and verbal abuse from the chief servant at his household, Oshin insisted on enduring it for the sake of her family. A sympathetic local teacher persuades the trader to allow Oshin to attend elementary school and bring the baby along. However, Oshin's classmates bully her and threaten to harm the baby. Oshin reluctantly stops going to school. However, when she is unjustly accused by the family of stealing money, she runs away, and for days suffers through blizzards as she walks back home to be with her mother, Fuji, nearly freezing to death.

Oshin is rescued by a man named Shunsaku, an Imperial Japanese Army soldier-turned-deserter, and a self-described "hunter". She stays with him during the long winter until the snow melts. She furthers her reading and writing skills under Shunsaku. When the blizzard subsides, they are found by an army unit and Shunsaku is shot dead. Oshin is then escorted by the soldiers to a hut and interrogated about Shunsaku. A senior soldier then comes into the hut and tells Oshin that the unit will escort her home. However, Oshin declines the offer, mentioning that she knows the way, and walks home on her own.

Working at Kagaya

Upon her return, Oshin is once again sent out to work as a babysitter, this time to Kaga-ya in Sakata. Things do not start well because of Oshin's association with the deserter, Shunsaku. She also clashes with Kayo, the family's eldest daughter and designated heir, who is the same age as she. But the matriarch and owner of Kaga-ya, Mrs. Yashiro, views Oshin as a role model to make Kayo more sensible and less like a spoilt child. Kayo resents this, but they eventually become good friends. Mrs. Yashiro sees the potential in Oshin and personally trains her in reading, writing, and arithmetic using the abacus. Kayo's mother is unhappy with the attention Oshin receives, feeling that it is socially out of place for a servant. However, she accepts Oshin into the family when Oshin saves Kayo from a falling utility pole.

Oshin stays at Kaga-ya for eight years until she turns 16. During this time, she is loved by everyone, including her co-workers. In the interim, Oshin's beloved grandmother dies, and the kind Mrs. Yashiro sends Oshin back home in time to spend the last moments with her dying grandmother. Her death steels Oshin's resolve to make something out of her life and to no longer be poor.

One day, a mysterious man, Kota Takakura, visits Sakata. While Oshin is looking for Kayo, who was at the beach, Kota uses Oshin as a foil as his girlfriend to elude the police. Kayo and Oshin's lives are changed by this man, the son of a wealthy landowner and an idealist who is a strong follower of socialism, and wants to better the lives of the indebted sharecroppers through political agitation and land reforms. Kota reveals to Oshin his political mobilization efforts and wins her over with his idealism and passion. Unfortunately, both Kayo and Oshin fall in love with Kota; however, Kota does not reciprocate Kayo's love, feeling that it is simply an infatuation, while he has declared his love for Oshin.

In the meantime, Mrs. Yashiro trains Oshin in the Japanese tea ceremony and other feminine arts to boost her chances of marrying well. She attempts to set Oshin up with the second son of a wealthy Sakata family, but the match falls through because of Oshin's secret love for Kota. Kayo, who has grown up to be passionate about painting and literature, has no interest in taking over Kaga-ya, nor in the feminine arts to improve her marriage prospects. She believes in marrying the man she loves. A rebellious Kayo leaves home on the day she was to meet her prospective husband, fleeing to Tokyo with a reluctant Kota. Heartbroken and feeling troubled by Kayo's decision to run away from home, and unable to reveal the truth to the Kaga-ya family about Kota, a guilt-stricken Oshin decides to leave Kaga-ya and return home.

Return to Yamagata

Upon returning, Oshin is re-united with her older sister, Haru, who was sent home from the textile mill where she had contracted tuberculosis. Haru's last wish is to see her secret love, her former supervisor, Hirano, who is persuaded to visit her. While visiting, Hirano reveals the poor working conditions at the textile mill and his failure to improve the workers' welfare for fear of losing his job. In the meantime, Oshin discovers that her father wants her to work as a barmaid to supplement the family's income. Haru warns Oshin that the agent touting the job had previously conned her fellow textile workers into prostitution. Haru persuades Oshin to run off to Tokyo, giving her a name and address in Tokyo and some money. Haru dies at the age of 19 in 1916. Oshin's mother Fuji, who had also returned home to take care of Haru, supports Oshin in her decision to go to Tokyo. Following her sister's death, Oshin runs off to Tokyo to follow Haru's dream of becoming a hairdresser.

Hairdressing in Tokyo

Oshin trains under Isho in traditional Japanese hairstyling. Two years into the apprenticeship, Oshin receives a letter from her mother informing her of the sudden death of Sayo, the younger sister of Kayo, from pneumonia. Oshin had also been her babysitter at Kaga-ya in Sakata. Oshin takes leave to visit the grieving family in Sakata. She is told that Kayo had not returned home and was somewhere in Tokyo. Kayo's mother pleads with her to stay behind but Oshin is unable to do so. Oshin is still hurting emotionally from when Kayo and Kota left Sakata two years earlier.

A year later, Oshin bumps into Kayo at a coffee house in the Ginza district while visiting prospective clients on a house call. Kayo had been working as a waitress at an upscale Ginza coffee house. Due to his agitation work, Kota was not usually around. Upon learning about Sayo's death, Kayo decides to visit her family in Sakata, staying there for a month.

In the meantime, Mrs. Yashiro arranges Kayo's marriage with the third son of an Osaka rice dealer, Masao, a graduate of the Tokyo Imperial University (present-day University of Tokyo), who is prepared to marry into the family to help the family business succeed. Kayo wants to leave for Tokyo to be present for Kota's return. But when Mrs. Yashiro collapses from a heart attack, Kayo reluctantly stays behind. She telephones Oshin to inform her when Kota returns to Tokyo. Oshin meets Kota when visiting Kayo's rented room to clean it. He tells Oshin not to let Kayo know that he is back in Tokyo, and tells Oshin that he does not love Kayo, and that he had only used her to fill the emotional void left behind when he was not able to be with Oshin. Oshin leaves for Sakata to attend Kayo's wedding. She does not update Kayo with news about Kota for the sake of Kaga-ya's future. Through Kayo, Oshin meets Ryuzo Tanokura, a seemingly rich textile trader who frequents the Ginza coffee houses. The third son of a prominent Saga family, Ryuzo decided to leave home for Tokyo to strike out on his own. Seven years Oshin's senior, Ryuzo falls in love with her, and the two get married despite initial opposition from both their parents.

Married life in Tokyo

Ryuzo's business begins to go downhill due to the post-war depression and his lack of business acumen. Oshin's attempts to improve business practices are badly received by Ryuzo who believes that business is a man's world. To supplement the family income, Oshin decides to return to work for Isho with Ryuzo's reluctant approval as married women did not usually work. As she increasingly takes on the role of breadwinner, Ryuzo feels undermined as he believes that it is the man's job to look after the family. He becomes increasingly despondent and indolent, and turns to alcohol and women, while Oshin turns a blind eye because of her love for him.

After a confrontation during which Ryuzo makes clear his bitterness, Oshin realises that her working to supporting the family had wounded his pride. She decides that it would be better for Ryuzo if she were to leave him. However, Oshin then discovers that she is pregnant. She decides to quit hairdressing to save her marriage. But with the loss of her income, the household comes to the brink of starvation before Ryuzo realises that he cannot let his pride get in the way of supporting his family. He borrows money to tide them over, and they start to think of a new business venture.

Realising they need capital to start a new business, Oshin persuades Ryuzo to allow her to try selling their cloth at a night market. After a rocky start, she manages to sell all their stock within 10 days with help from gang ringleader Ken. They decide to use the proceeds to start a new business selling Western-style children's clothes designed by Oshin. Due to lacklustre business, Ryuzo arranges to sell their products at Onoya, a large local shop. The affordable clothes are sold out at Onoya on the first day, and Ryuzo begins to expand production despite Oshin's misgivings.

With Oshin's baby arriving soon, Ryuzo arranges for Fuji to visit. Oshin gives birth to a healthy baby boy whom they name Yu ("courageous"). After Fuji leaves, Ryuzo's father also pays a visit to see the baby. The couple learns that Ryuzo's mother Kiyo still refuses to accept Oshin. Ryuzo decides to borrow large sums of money to buy a plot of land and build a large factory, convinced that a successful business will prove his worth even as a third son and persuade his mother to accept their marriage.

One day, they receive an unexpected visit from Kayo who says she has come to see the baby. However she soon reveals that she wishes to run away from her unhappy marriage in Sakata and find Kyota, whom she has learned is at his parents' house in Tokyo. Kyota agrees to meet with Kayo who expresses her desire to be with him. However Kyota tells her that the only reason he met with her was to apologise for the way that he had left her. With his continued involvement in the workers' movement, he was not in a position to have a relationship. Kayo finally realises what a fool she has been all these years and that Oshin was the one Kyota had loved. Kayo resolves to return to Sakata and bear an heir to carry on the family business.

After months of building work and preparation, it is finally the day of the grand opening of the new factory. However disaster strikes, and the Great Kantō earthquake and subsequent fire destroy their factory and house. Their faithful retainer Genji dies protecting Yu, who survives unscathed.

With only shattered dreams and debts, Ryuzo decides that they have no choice but to return to his family in Saga. Oshin is fearful of the treatment she will receive at the hands of her mother-in-law and urges Ryuzo to try once again to build their lives in Tokyo. But after so much disappointment, Ryuzo no longer has the will to try again. Although Oshin wants to stay on in Tokyo with Yu, her mother (whom the Kagayas have sent to Tokyo to find Oshin) persuades her to stay together with Ryuzo for the sake of their son.

Hardship in Saga

Upon their arrival in Saga, they are greeted warmly by Ryuzo's father, who is overjoyed that they are unharmed. But Oshin receives a barrage of criticism from Kiyo, who blames her for all the disasters that have befallen Ryuzo, including Genji's death. Ryuzo's eldest brother makes it clear that Ryuzo will not receive another penny from the family since he took his share of the inheritance when he left home. Kiyo informs them that they will have to work the fields to earn their keep – the very life that Oshin thought she had escaped when she left home.

Kiyo is controlling and domineering, criticising Oshin at every turn while chiding Ryuzo for not taking charge of his wife. As Ryuzo and Oshin have no money, they are unable to purchase even simple items like soap, needles and thread. Oshin is keen to offer her services as a hairdresser to the villagers, but Ryuzo and Kiyo refuse to allow this as it would bring disgrace to the family. Ryuzo asks Kiyo for money, but she scolds Oshin for complaining to Ryuzo, leading to marital discord between the couple.

Oshin wants to leave and go to the nearby town or back to Tokyo, but Ryuzo will not hear of it as he is worried about how they will support themselves without any money. He decides to join a scheme to reclaim land from the sea, which he will own after 10 years. Oshin is concerned about such a high-risk endeavour but Ryuzo presses ahead nonetheless. While Oshin continues to be bullied by the household, Ryuzo becomes fed up with Oshin's complaining and begins to side with his mother. He even moves to a separate room, much to Kiyo's delight, who encourages him to divorce Oshin.

One day Oshin receives a letter from Isho who has returned to Tokyo after the earthquake and will be opening another hairdressing shop in a few months. Oshin decides to join her in Tokyo when the time comes. As she plans her escape, Oshin discovers she is pregnant with their second child.

On the day that she is due to catch a train to Tokyo, Ryuzo finds out and intercepts her. When he is unable to persuade her to stay, he struggles with her to take their son from her. Oshin falls and hits her head, paralysing her right side. She has no choice but to return to Ryuzo's home.

The partial paralysis in Oshin's hand renders her unable to cook, sew or look after Yu, who is now cared for by Kiyo. As the visible injury was to her head, not her hand, the family including Ryuzo begins to think that Oshin is feigning the injury. Aware that she is a burden to the family, Oshin cannot bring herself to tell anyone that she is pregnant. However Ryuzo finds out that she is pregnant, which brings them closer together once more.

Unfortunately, Kiyo learns that Oshin had planned to run away and wants to throw her out of the house. Ryuzo reveals that Oshin is pregnant and that she must therefore stay with the family. But Kiyo believes it will be inauspicious for Oshin and her own daughter Ritsuko, who is also pregnant, to give birth in the same house at the same time – it is said that one of the births will not go well. Oshin agrees to move into the shed, which Kiyo hopes will prevent the superstition from coming true.

After a difficult labour, Ritsuko delivers a healthy baby. Oshin goes into labour at the same time, but the malnutrition and forced labour have taken their toll – Oshin's baby is too weak to survive. With this latest calamity, Oshin's mind becomes unhinged.

As Ritsuko does not have enough milk for her baby, Kiyo asks Ryuzo to let Oshin breastfeed the baby. While he is initially taken aback by the idea, he agrees thinking that it might comfort and restore Oshin's mind. After feeding the baby, Oshin comes back to her senses and agrees to continue feeding the baby. Kiyo is immensely touched and grateful and promises to treat Oshin better.

After a month, Ritsuko returns home with the baby. Unbeknownst to the family, Oshin had already decided to leave the household as she realised that she would have to work the fields for the rest of her life in Saga and would never amount to anything. Now that her duty is done, she informs the family that she will be leaving for Tokyo. Ryuzo agrees to let her leave as a sign of love and they part believing that they will be together again one day. Ryuzo's father and eldest brother give her some money to help her in Tokyo. However Kiyo is furious and refuses to let her take Yu with her.

While preparing to leave the next morning, Kasumi, Ryuzo's sister-in-law tells her that she will bring Yu to her. As Kiyo refuses to hand over Yu, Oshin has no choice but to trust her sister-in-law. Kasumi turns out to be true to her word and stole Yu while Kiyo is out and Oshin leaves for Tokyo with Yu.

Night market in Tokyo

Oshin is warmly welcome by Isho in Tokyo. But Oshin discovers that her hand is still not recovered enough for her to resume hairdressing. Ringleader Ken helps her to set up a food stall at a night market and rent her own house. All seems well until one day a woman bursts in to Oshin's house when Ken is there. She turns out to be Ken's partner and accuses Ken of having an affair with Oshin and spending all his money on her. Ken admits that he is in love with Oshin, but says he has done nothing wrong. Oshin is shocked and saddened to learn that she has been the cause of another woman's grief, and uncomfortable about Ken's feelings for her. She worries that rumours may reach Ryuzo in Saga. Despite Isho's entreaties for Oshin to stay with her, Oshin cannot bring herself to be a burden to Isho, and decides to give up the stall and return to her family home in Yamagata.

Fuji is overjoyed to see her daughter Oshin after 4 years, but Oshin's brother's reception is cold when he realises that she intends to stay. They do not have enough food for her and Yu. Fuji's attempts to protect Oshin widen the rift with her brother and his wife. Oshin manages to find work helping other farmers.

Running an eatery in Sakata

One day, Oshin is informed that the madam at Kagaya is seriously ill and unlikely to recover. Oshin visits the Kagayas in time to bid the madam a final farewell. Masao, Kayo's husband comes to offer incense, but Kayo wants him sent away as she is unable to forgive him for having a child with another woman. Oshin convinces Kayo to give Masao one more chance as Kagaya needs an heir. Plans are made for Masao to move back into the Kagaya household.

When Kayo learns of Oshin's situation, she persuades Oshin to stay in Sakata and open a shop. Oshin decides to open a simple eatery, with a loan from the Kagayas.

Oshin's eatery has no customers on its first day. After advertising for 3 days, the eatery begins to do well. As Kayo's father and husband have now taken over the business, Kayo decides to help out at Oshin's eatery. Kayo is surprised and touched when Masao agrees to let her do so.

One evening a drunk customer comes to the eatery demanding sake. Oshin informs him that she does not serve sake and asks him to leave. The customer becomes increasingly belligerent until Kayo finally brings him sake, telling Oshin that they will be able to make more profit this way. Oshin is reluctant as she did not want the eatery turning into a bar.

Eventually the local yakuza turn up at the eatery to stop Oshin from selling sake as her low prices are hurting the business of other bars. As they begin to destroy the shop, Kayo is terrified and tells the yakuza they will comply, but Oshin is utterly adamant that she will not give in to them. Insisting that they take the matter outside, the yakuza are surprised when Oshin gives the formal yakuza greeting of Ken's house in Tokyo. Soon, they are all enjoying warm sake in Oshin's eatery, where the local yakuza express their admiration for Oshin, calling her sister and promising their protection. Oshin confesses to Kayo later that in fact she is not part of Ken's yakuza house, but had learned the greeting from him.

Oshin's eatery is now doing well enough to support Ryuzo, Oshin and Yu. Oshin has been writing to Ryuzo regularly for a year but has never received a reply. Little does she know that Kiyo has been intercepting Oshin's letters, so Ryuzo does not even know where Oshin lives. Oshin decides to write to Ryuzo one last time. If Ryuzo does not reply, she will give up on him.

One evening, Kyota comes to Oshin's eatery, not realising that it is run by Oshin. Kayo, who has now gotten over her infatuation for him, tells Kyota that Oshin and Yu have been abandoned by Ryuzo. Kyota tells Oshin that the labour movement is now legitimate and he no longer needs to hide from the police. He offers to become a father to Yu.

But all too soon, the government cracks down on the labour movement, making it once again difficult for Kyota to have a family. Oshin tells Kyota that just hearing his words of love have erased the years of bitterness from her heart. Kyota tells Oshin that although they will not marry, he will always look after them. Oshin says this is enough for her. Kyota says he will write to Ryuzo to make his intentions known.

Back in Saga, in a bid to persuade Ryuzo to give up on Oshin and remarry, Kiyo shows him Kyota's letter, in which he mentions that Oshin sent Ryuzo many letters but did not receive a reply. Kiyo says that Oshin must have been lying to Kyota to make herself look good. Unable to bear the deceit any longer, Kasumi finally shows Ryuzo a stack of Oshin's letters that Kiyo had intercepted but which she had saved. Ryuzo tells his mother to give up on the idea of his remarriage. Oshin is his wife and once he reclaims the land, he will ask Oshin to return. In the meantime it is better that she continues to work in Sakata rather than suffering in Saga. If they are faithful to each other, they will be together again one day. Ryuzo writes to Oshin and sends her some money.

Oshin is overjoyed to finally receive a letter from Ryuzo. However Kyota is astonished that Ryuzo is staying in Saga instead of coming to Sakata. But Oshin understands that Ryuzo has his male pride – he wants to succeed at the land reclamation. Also, Oshin knows that Ryuzo would not like running an eatery.

One evening, two drunken customers get into a knife fight in the eatery. Kyota wants to intervene but Oshin says she will handle it as they are her customers. Not only does she manage to persuade them to take the fight outside, she even gets them to pay their bills. Watching Oshin scrabble on the floor picking up money and crockery, and fending off the advances of drunken customers, Kyota becomes increasingly worried. He points out that if Ryuzo does not like running an eatery, things could be difficult if he were to come to Sakata. Kyota advises Oshin to consider a different trade.

Selling seafood in Ise

Kyota arranges for Oshin to stay with his aunt in Ise and sell fish instead. Oshin soon picks up the trade and gains customers with her low prices and resourcefulness. She dreams that one day Ryuzo will join her and Yu in Ise.

One evening, a typhoon hits Japan, washing away the land in Saga that Ryuzo had been painstakingly reclaiming for the past 4 years. With his dreams shattered once more, Ryuzo leaves Saga to forge a new life.

As Oshin sets off to sell fish one morning, she sees a familiar figure some distance away – it is Ryuzo. When she catches up to him, he reveals that he is on his way to Manchuria, where he has friends, to start again. He had planned to come to Ise to divorce Oshin but when he saw her and Yu, he was unable to do so. He tells her to wait for him. As he turns to leave once more, he sees Yu and they have a tearful reunion.

On the morning that Ryuzo is due to leave for Manchuria, he helps her push her cart to town and Oshin bids him goodbye. However, struck by the heaviness of the cart which Oshin pushes for 7 miles a day, Ryuzo decides to follow her to see what her life selling fish is like. When he sees how hard she has to work, he decides that he has no choice but to stay to help her. Oshin is overjoyed to be together as a family once more. With help from Oshin's landlady, the couple start a fish shop in town. Ryuzo begins to learn about fish and how to prepare and cook it.

Oshin writes to Saga to update Ryuzo's parents on his whereabouts. Kiyo is furious and asks her husband to go to Ise to retrieve Ryuzo, but he tells Kiyo that she must never separate them again. Kiyo finally realises that Ryuzo's love for his wife is greater than his love for his mother. She sends Ryuzo his possessions, along with a letter encouraging to make a new life in Ise with Oshin. Oshin is overjoyed that Kiyo has finally forgiven her, and is determined to make the shop a success so that Ryuzo's parents can visit one day.

A new beginning, and an end

Fuji is getting older and weaker, and is unable to do much work in the fields. Her son and daughter-in-law begin to resent having a useless mouth to feed. When Oshin writes inviting her mother to visit them in Ise, Oshin's brother is keen for his mother to stay with Oshin permanently. Just as Oshin and Ryuzo are wondering how to persuade her mother to stay with them, Oshin discovers that she is pregnant for the third time. Fuji is worried about being a burden as she is no longer strong enough to work. But Ryuzo's and Oshin's heartfelt entreaties convince her to stay, at least until Oshin delivers the baby. Oshin is also delighted to learn that after 10 years of marriage, Kayo is finally pregnant with the Kagaya heir.

Oshin gives birth to a healthy baby boy, Hitoshi ("benevolence"). However, minutes after the birth, Fuji collapses. They discover that she has leukaemia, which is incurable. To fulfil her mother's last wish, Oshin brings her home to Yamagata, carrying her on her back as Fuji is too weak by now to walk. Fuji dies in Oshin's arms in her own home.

The downfall of Kagaya

Oshin learns that Kayo's husband Masao has committed suicide. Kyota appears asking Oshin to bring 100 yen to Kayo who is living in Tokyo. When Ryuzo sees the address, he tells Oshin that before the earthquake, this was a bad neighbourhood with many brothels. Oshin is adamant that Kayo would never turn to prostitution no matter how bad things became. But Ryuzo warns Oshin to prepare herself for the worst.

Oshin enlists Ken's help to find Kayo in Tokyo's red-light district. Now a prostitute, a broken and dissipated Kayo reveals that Masao had gambled Kagaya's entire fortune away on rice derivatives that went awry. She and her parents had come to Tokyo but her mother fell ill after her father died, so Kayo had sold herself into prostitution to pay for her mother's medical bills. Unable to even bring their bones back to Sakata for a proper burial, Kayo now lives for her son Nozomi.

Unable to raise the 1,000 yen required to buy Kayo out of prostitution, Oshin is determined to at least bring Nozomi to Ise. But when she and Ken return to the brothel the following morning, they discover that Kayo has died. She had a weak stomach but drank a large amount of sake the night before and vomited blood, eventually choking to death.

Oshin finds a letter from Kayo among her belongings. Kayo knew she did not have long to live, but after meeting Oshin again, she knew that she could entrust Nozomi to Oshin's care. Oshin swears that from that day on, she will regard Nozomi as her own son.

The family grows

Oshin brings Nozomi back to Ise, and to a supportive Ryuzo. They bury the bones of Kayo and her parents in Ise so that Nozomi can visit them; he can bring them to Sakata one day if he chooses.

One day Kyota comes to Ise. He asks Oshin for the location of Kayo's grave so that he can pay his respects in the morning. Oshin says she will meet him there so that he can see Nozomi but he tells her no, in case he is followed by the police. The next morning, Oshin waits for him at the grave with Nozomi and Hitoshi, but when Kyota arrives he is captured by the special policemen who accuse him of planning to escape to Moscow. The policemen allow Kyota to light incense for Kayo before they take him away. Kyota pretends that he does not know Oshin to protect her, but Oshin is devastated to see Kyota being taken away.

4 years later, Ken visits Ise on his way to Osaka. He is accompanied by Hatsuko, a 9-year-old girl from Yamagata whom he intends to sell to a brothel in Osaka as a cleaning girl. Ken is related to her parents – tenant farmers who had a bad harvest this year and had no other choice but to try to sell their daughter for 50 yen. Hatsuko's hard fate and cheerful resourcefulness remind Oshin of herself when she was a girl, and of Ai, the baby girl Oshin had lost who would be the same age as Hatsuko had she lived. The couple decide to take Hatsuko in, paying Ken the 50 yen. Ryuzo and Oshin treat Hatsuko as part of the family, even arranging for her to continue her education.

Hatsuko grows closer to Oshin's sons. Soon, Yu is about to take an important examination. Yu tells Hatsuko that he must pass the examination because his mother has always worked so hard to look after him. The night before the examination, Oshin and Ryuzo are awakened by the sound of running water. When they go into the courtyard, they discover Hatsuko pouring cold water on herself while praying for Yu to pass his examination, a village superstition. The family is touched by her sincere, if foolish, actions.

The day before Hitoshi and Nozomi start school, Oshin decides to tell Nozomi that he is adopted and that his birth parents are the Yashiros. She takes him to visit his parents' grave. Nozomi seems to takes the revelation well, but on his first day at school he is bullied for being an orphan and runs away from home. The family search all day and night for Nozomi, and a devastated Oshin ends up at Kayo's grave, where she finds Nozomi. When she sees him, she slaps him for not being strong enough to face up to the bullies. She tells Nozomi that life will be full of difficulties. He promises to go back to school, and Oshin tells him again that the whole family sees him as one of them. Oshin brings Nozomi home where he is warmly welcome by everyone.

Oshin discovers that she is pregnant once more. Ryuzo is delighted, but concerned about making ends meet, he suggests sending Hatsuko back when her 3-year contract is over and she has graduated from junior high school. In any case Hatsuko's parents must be waiting for her. Oshin is reluctant to let Hatsuko go and feels that they should let her decide for herself when the time comes.

Oshin gives birth to a healthy girl whom they name Tei ("happiness"). Having reached the end of her contract, Hatsuko feels that she should go home because otherwise she will be a burden to the family with the addition of the baby. But when Ryuzo and Oshin realise that Hatsuko would in fact prefer to stay, they joyfully welcome her to the family.

Japan enters war

Japan begins to enter a period of military rule. Ryuzo gets involved with the military to raise more money along with the fish shop, something Oshin opposes but relents when she puts his interests at heart and decided that they need the financial support. Due to the military propaganda during this time period, Yu begins to side with the military and support the Sino-Japanese Wars.

When Yu began to apply for high school, he asked Ryuzo for permission to join the Military Officers Academy, where students are taught to become a military officer to fight the war. Oshin overhears the conversation and intervenes just when Ryuzo approves. Due to Oshin's convictions of pacifism, Oshin gets desperate to keep Yu from applying. When Yu remains firm on his decision to apply, Hatsuko reminds him that Oshin doesn't want him to fight since she has gone through adversity with him when he was still a child. To humor Oshin, Yu decides to apply to a school in Kyoto to study Humanities instead of applying to the Military Officers Academy.

As 1940 arrives, food rationing is on the rise to support the war effort. This was also the time when the black market surfaced to sell rationed goods. When the black market began to sell illegal imports of fish, Oshin is forced to close down the store to prevent trouble. Hisa moves to Tokyo due to the lack of fishermen and rations. Subsequently, Oshin's family moves to a new house that was previously owned by a man working with the military, who relocated in Pyongyang. When Yu came by to visit, Yu and Hatsuko profess their love for each other, something that Ryuzo opposes. Ryuzo also gets involved in the military committee, where he encourages boys in the area to enlist, and begins to manage a uniforms factory. Life continues as usual until Yu visits again in 1943.

Yu reveals to Ryuzo that student-exemptions for military drafts have been lifted, and later he breaks the news to Oshin that he must enlist within one month. A shocked Oshin begins to cry in front of Yu and feels like she betrayed Shunsaku, the military deserter who instilled pacifism in her as a child. After one month, Yu leaves in uniform.

As air raids began to be feared, Ryuzo mulls whether to send Tei to the countryside where she won't be affected by the air raids. Ryuzo sends her to a home of one of his factory workers where Tei gets mistreated and neglected. As Japan begins to lose, Yu's regiment is sent to the Philippines, where he would be safer due to the air raids in Japan. Hitoshi begins to support the war effort and declares that he wants to join the kamikaze squad, something both Oshin and Ryuzo oppose. However, Hitoshi sneaks out and joins the kamikaze.

Oshin's family begins to experience their first air raid and her first priority is to keep the house from burning down instead of evacuating into a bomb shelter. Before the bombs ignite into flames, Nozomi and Hatsuko get containers of water ready and diligently fight the fire but see that the factories they manage are burning down. After the air raid, Oshin receives a telegram stating Yu has died in the Philippines. Oshin refuses to believe until she has seen his body, and been informed by his best friend, who confessed Yu had malaria. Soon, Japan surrenders to the Allies in 1945.

However, Ryuzo soon finds out that his company is completely out of money. Feeling scared, disappointed, and angered that he betrayed Oshin, he is found on a mountain by a commoner, having killed himself, in spite of knowing Oshin and his family needed him. Oshin was now a widow, and had lost two members of her family because of the war. Eventually, she successfully brought back home Tei with her. Hatsuko, not being able to handle everything, leaves to Tokyo, to work at a rice store.

New trouble arises when the original owners of the house return from Pyongyang and demand their house back. They still hold the deed for the property and the paperwork Oshin produced were signed by the Japanese military and was not worth anything. The Tanokura family is forced to co-habit and are miserable. After being arrested for selling food on the street to earn money for her remaining family, Oshin gets kicked out of her house by an angry landlord. This entire war motivated Oshin to work as hard as she can, for her family's sake at least.

Mrs. Hisayama reenters their life and she visits Oshin to let her know that she is going to start her fishing business in Ise. She invites Oshin and her family to come live with her and Oshin happily accepts.

Seafood and vegetable store

A decade after the war, Oshin is now 50 years old, and owns a seafood and vegetable market with Hitoshi. Ken visits Oshin, telling her she must visit Tokyo as soon as she can. Hatsuko lied when she said she worked at a rice shop. She really works at a brothel, greeting soldiers every night. This was supposedly her rebound from Yu. Oshin finds her in the brothel, asks Ken to drag her out, and slaps her. Oshin manages to convince Hatsuko to return home with her and to forget everything that had happened in Tokyo. Shortly afterwards, they hire a sweet girl named Yuri to work with them, as they drop by people's houses and deliver their food. Hitoshi has decided that he wants to become a businessman and make a living from there. He also tells Yuri that one day, he and Yuri will get married. Few months later, Hitoshi leave to Tokyo to work as a clerk only to know that he cannot get a job as a delivery man without a college education. He drifted in Tokyo for several months and returned home. He met his future wife, Michiko, a daughter of a rich businessman. Later Yuri learned about it and run away from home. Oshin is very upset of Hitoshi and opposed to the marriage of Hitoshi and Michiko.