On February 24, 1483, Tsugumitsu (継満) SUWA from the Suwa clan (the ohori family), Okiharu KANASASHI (the Suwa shimosha Kanasashi clan) and Tsugumune (継宗) TAKATO (the Takato clan) carried out a revolt (Bunmei no Naiko) and because Masamitsu, Yorimitsu's father and older brother were killed, Yorimitsu took over as head of the family at the age of 10.
文明15年1月8日_(旧暦)、一族の諏訪継満（大祝家）・金刺興春（諏訪下社金刺氏）・高遠継宗（高遠氏）の反乱（文明の内訌）によって父政満と兄を殺されたため10歳で家督を相続した。