Kotetsu is a Hidden Leaf chuunin who specializes in genjutsu. He and his friend, Izumo, held their own unofficial first test at the beginning of the chuunin exam. They used genjutsu to switch the room numbers and trick the candidates for the exam. Kotetsu and Izumo later became the fifth Hokage's assistants, the pair often run errands for Tsunade.
Kotetsu was a member of the task force that Tsunade set out to capture Hidan and Kakuzu when they entered the Land of Fire in search of Uzumaki Naruto. Kotetsu was in a team with Asuma, Shikamaru, and Izumo. Kotetsu and his team met up with the two Akatsuki members and attempted to ambush Hidan and Kakuzu. Kotetsu summoned a large club type weapon and attempted to attack Kakuzu while Izumo had him caught in a jutsu, but failed. Kotetsu, Izumo, and Shikamaru were over powered by Kakuzu and forced to watch Hidan kill Asuma.