Ujichika was the son of Imagawa Yoshitada. In 1476 Yoshitada invaded Tôtômi Province and defeated the Katsumada and Yokota clans. On the return to Suruga, however, he was waylaid at Shiokaizaka and was attacked and killed by the remnants of the two families he had just defeated. A succession dispute between supporters of Yoshichika's infant son Tatsuomaru (Ujichika) and his cousin Oshika Shingorô Norimitsu developed. Ôgigayatsu – Uesugi Sadamasa and the so-called Horigoe Kubô (Ashikaga Masatomo) both became involved, and the Imagawa found themselves standing at a crossroads. Ise Shinkûrô (the future Hôjô Sôun) proposed that until Ujichika has his coming of age ceremony, Oshika Norimitsu act as a regent in his name. This averted armed conflict within the Imagawa, at least temporarily. However, when Ujichika turned 17, Norimitsu would not turn over control of the imagawa clan to him, and hostilities resumed. Shinkûrô attacked Norimitsu's mansion on Ujichika's behalf and once Norimatsu was defeated, Ujichika assumed his position as head of the clan. He gave asylum to Ashikaga Yoshizumi after the latter fled Kyoto in 1491 and afterwards escorted him back. A capable leader, he spent much time campaigning in Tôtômi and Mikawa, strengthening the position of the Imagawa on the Tokai Coast. He died of illness in 1526 and was succeeded by his eldest son Ujiteru. Ujichika is remembered for sending three of his six sons to various temples to become monks and for building Nagoya Castle in Owari in 1525 - both of which were considered somewhat unusual - the latter because the Imagawa had only the most tenuous of holds over Owari Province.
He composed the Imagawa house code, the Imagawa Kana Mokuroku, in 1526. Clauses included such stipulations as the punishment for unlawful entry of another's residence (article 7), the imposition of capital punishment in violent quarrels between retainers (article 8), the accountability of the parents of children (of retainers) involved in fights (article 11), regulations concerning the private sale and leasing of land (articles 13-15), debt repayment (article 17), and forbidding retainers of the Imagawa to arrange marriages with houses outside the Imagawa domain (article 30). Ujichika's sons included Ujiteru (d.1536), Hikogoro (d.1536), Yoshizane, Yoshimoto, and Ujitoyo.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005