Itami Kunisuke served as a bushō during the Sengoku period. He was a retainer of the Hosokawa-Keichō family who were the kanrei, or deputy shōgun, of the Muromachi bakufu. Kunisuke was the head of the Itami clan and lord of Itami Castle in the Kawabe District of Settsu Province. This was later known as Arioka Castle.
Kunisuke is regarded to have been born as the son of Itami Motosuke. His common name was Hyōgo-no-suke. His childhood name was Masasuke, later, he received one of the characters from the name of Hosokawa Takakuni (the military governor of Settsu and deputy shōgun) and adopted the name of Kunisuke.
Similar to his father, Kunisuke served as a bushō for Takakuni. In 1520, when Hosokawa Sumimoto and Miyoshi Yukinaga attacked Koshimizu Castle in Settsu, Kunisuke served in the rear guard of Takakuni’s army. After the death of Motosuke, Kunisuke continued to serve as a capable bushō for Takakuni.
Takakuni and Sumimoto, along with Hosokawa Sumiyuki, were all three adopted sons of Hosokawa Masamoto (the former deputy shōgun). Following Masamoto’s assassination on 6/23 of Eishō 4 (1507) in a plot by Sumiyuki (after his removal from the line of succession) known as the Lord Hosokawa Incident, factions supporting each one of the adopted sons engaged in a succession struggle. A short while after the assassination, Sumiyuki was killed, but the conflict between Sumimoto and Takakuni lasted for decades until the Collapse at Daimotsu on 6/4 of Kyōroku 4 (1531) when Hosokawa Harumoto (Sumimoto’s son) and Miyoshi Motonaga (Yukinaga’s grandson) finally defeated Takakuni. Kunisuke was said to have died in this conflict.