Katsuichi is the sensei of Miyamoto Usagi. He rebelled against the eight kyoto styles and formed his own school, closing this down due to lack of quality of students, and became a hermit living in the mountains near Usagi's village.

Usagi became his student after witnessing the defeat of students from the Dogora fencing school where he was to train. He trained the young boy hard, and entered him in a tournament at the dogora school, which the boy won.

Often harrassed by members of this school, he was now more so, because of their loss of face. A band of students led by Higashimori finally came to avenge this. During the fight, Higashimori dishonourably attacked Katsuichi, putting out his eye and sending him over a cliff.

Katsuichi was rescued by a pair of boys who nursed him back to health, and whom he subsequently took on as students. Usagi was surprised to see his old sensei when his wanderings took him back past his sensei's hut. He had thought the old man slain when sent over the cliff by Higashimori. Katsuichi resides as he ever did, in his home, teaching the ways of bushido to students he deems worthy to learn.