Higashimori was the chief instructor of the Dogora fencing school. He was an anthropomorphic cat whose distinguishing feature was his very long face.
Higashimori was present at a tournament sponsored by the Dogora fencing school, which Katsuichi attended with his student, Miyamoto Usagi. Higashimori thought that Katsuichi was a fraud and did not understand why Genjiro, the head of the Dogora school, allowed him to participate. Genjiro explained that turning away Katsuichi would lose the Dogora school face before their sponsor, Lord Mifune, but instructed Higashimori to make sure that Usagi lost. However, Usagi was a better swordsman than the Dogora pupils and won the tournament.
Three months after the tournament, Higashimori's anger with Katsuichi reached its pinnacle, and he led a group of Dogora students to attack Katsuichi and Usagi. Higashimori attacked Katsuichi dishonourably, blinding him in his left eye and sending him toppling off a cliff into a river. However, Usagi had slain the students sent to kill him. Enraged at his sensei's apparent murder, Usagi slew Higashimori.