Eldest son of Hatakeyama Shigetada of Musashi Province, praised as the "model of eastern warriors" and the Kamakura Shogunate's most upright warrior. Shigeyasu was raised under his father's exemplary influence. In 1205, Hojo Tokimasa's wife Maki no Kata, who resented Shigeyasu because of a feud with her son-in-law Hiraga Tomoyoshi, slandered Shigeyasu to Tokimasa as plotting rebellion. Shigeyasu was lured to Yuigahama in Kamakura and killed by Miura Yoshimura. When Shigetada received the news, he rode south from Musashi to defend his name, but was surrounded at Futamatagawa (present-day Yokohama) by a vastly superior Hojo force. He fell fighting to the last with only 136 mounted men. This conspiracy was later exposed as completely false. Masako and Yoshitoki were outraged: Maki no Kata was exiled, and Tokimasa was compelled to retire as a monk. The tragedy of the Hatakeyama father and son directly triggered Tokimasa's downfall and the rise of the Yoshitoki-Masako regime.

A young warrior who inherited his father's valor and loyalty. Tragically caught in Hojo machinations, he was killed without a chance to defend himself.

The false charges against the Hatakeyama father and son symbolize the tragic power struggles of Kamakura. The incident led to Tokimasa's exile and the rise of Yoshitoki and Masako.