Said to be the daughter of Ryobashi Taro, she was Yoritomo's beloved concubine. Her relationship with Yoritomo reportedly began during his years of exile in Izu, when she became a cherished presence for the lonely outcast. Even after Yoritomo's uprising and his marriage to Hojo Masako, the relationship continued: Yoritomo set up a residence for Kame in Kamakura and visited regularly. In 1182, when Masako discovered this, she was consumed with fury. She ordered her father Tokimasa's retainer Maki Munechi to demolish the house—belonging to Minamoto no Nakaie—where Kame was staying (the Kame no Mae Incident). Kame escaped, but the residence was wrecked. Yoritomo, enraged by the high-handed act, had Munechi's topknot cut off in an unusual public shaming. Tokimasa, blamed for permitting his daughter's action, temporarily withdrew from Kamakura, straining relations with Yoritomo. The episode is recorded in detail in the Azuma Kagami and remains one of the most vivid illustrations of Masako's fierce jealousy and the intensity of her bond with Yoritomo.

Little is recorded about her personality, but Yoritomo's lasting affection suggests she was intelligent and charming. She became a victim of Masako's wrath.

The Kame no Mae Incident is the quintessential episode illustrating Masako's jealousy, vividly recorded in the "Azuma Kagami" as a snapshot of human drama in the Kamakura Shogunate.