[2] The Kutsuki were a powerful clan at Kutsuki-tani (朽木谷), Takasima-gori, Ōmi Province.
At the age of two, Mototsuna succeeded when his father died in battle.
In 1570, Mototsuna helped Oda Nobunaga when he attacked Asakura clan and retired through Kutsuki.
[2] In 1600 at the Battle of Sekigahara, at the start Mototsuna took part in Ishida Mitsunari's force belonging to Otani Yoshitsugu.
However, acting in concert with Kobayakawa Hideaki, Mototsuna, along with Wakisaka Yasuharu, Ogawa Suketada and Akaza Naoyasu, betrayed Mitsunari.