Service under Nobuhide

It is said that he was born in Iwasaki Village, Owari Province. Hidetaka served Oda Nobuhide from an early stage. His given name's kanji spelling, with 秀 for hide, is considered to be from Nobuhide's name, which was also spelled with 秀 for hide.

In August 1542 at the age of 16, he participated in the first Battle of Azukizaka as a vassal of Nobuhide. He fought with ashigaru commander Yuhara (由原), who was the forerunner of the Imagawa clan, and defeated him at the battle's end.

Hidetaka's Uma-jirushi (right side)

Service under Nobunaga

After Nobuhide's death, he also served Oda Nobunaga and became the head of "Kuro-horo-shu" (bodyguard unit in black). In 1558, when Nobunaga summoned his younger brother Oda Nobuyuki to Kiyosu Castle to murder him, he carried out the assassination of Nobuyuki.

He participated in the Battle of Okehazama in May 1560. He followed Nobunaga, who suddenly rushed out, with only four other vassals: Iwamuro Shigeyasu, Hasegawa Hashisuke, Yamaguchi Hidanokami, and Katō Yasaburo. It is said that Mōri Yoshikatsu defeated Imagawa Yoshimoto in the battle, but there is also a different theory that Hidetaka killed Yoshimoto.

In the summer of 1565, he was ordered to attack Mino Sarubami Castle with Niwa Nagahide. The castle's owner, Tajimi Shuri-no-Suke, used the advantage of the land to protect the castle well, but Nagahide occupied the neighboring mountain and cut off the water source, and Hidetaka launched an onslaught and dropped the castle. In the battle of Dōhora castle, on September 28, 1565, he breached the inner citadel first and forced the enemy commander Kishi Nobuharu to commit suicide. After the war, he was given Sarubami Castle as a reward for his conduct in the Mino battle, and the castle's name was changed to Katsuyama. Shortly afterwards, the castle town of Sakahogi, Chozoji, was designated as Kawajiri's family temple. He also allegedly supported the reconstruction of Daisen-ji Temple, which was burned down in the war.

In early 1569, he and Sakai Masahisa were sent to tell Imai Sōkyū to hand over the testimony of Sakai Kitasho. In August of 1569, he participated in a battle with Kitabatake clan based in Okawachi Castle, Ise province. At this time, he was in charge of patrolling the Oda clan army headquarters, along with Sugaya Nagayori, Harada Naomasa, Nakagawa Shigemasa, and Maeda Toshiie. The name can be seen in the draft letter of sympathy sent by Munehisa Imai to the Oda clan generals on September 6, 1569.

On February 19, 1570, Imai Sokyu sent urgent news that Akagi Nobuyasu defeated the army of Miyoshi clan in Awaji province. In the draft letter, the names are listed alongside Kanamori Nagachika, Takei Yūan, Sakai Kōsai, and Sugaya Naganori, and it can be seen that he was recognized as one of Nobunaga's representative aides at that time. On March 6, 1570, Nakayama Takachika and Kanroji Tsunemoto visited Nobunaga, but Hidetaka responded due to his absence and received 30 swords as a reward. On June 28, 1570, he served in the Battle of Anegawa, and in the siege of Sawayama Castle, where Isono Kazumasa, a vassal of Azai Nagamasa, was occupying after the main war, he set up in Nishi-Hikoneyama, one of the attached castles. At the Siege of Shiga in September 1570, he entered the fort of Anota with Sakuma Nobumori, Akechi Mitsuhide, Murai Sadakatsu, and Sassa Narimasa, and played a part in the Siege of Enryaku-ji Temple on Mt. Hiei.

In February 1571, he entered Sawayama Castle after Isono Kazumasa moved out, and since then he was active as a castle general with Niwa Nagahide. In September 1571, Nobunaga ordered for the Tendai Temple affiliated with Enryaku-ji at Mt. Hiei to be burned down, and Hidetaka and Nagahide burned down Saimyōji temple.

In 1582, while planning the Conquest of Kōshū, Nobunaga assigned an army to his eldest son, Oda Nobutada, and had him invade Shinano and Kai Province. Hidetaka, along with Takigawa Kazumasu, became a military commander.