Mumm-Ra once told him that the Thundercats were evil invaders and he set out to destroy them. He was then convinced by Lion-O that they are good and helps them.
Hachiman lives his life by the code of Bushido, a strict code of honour that shapes his every action. As such, Hachiman is both quick to anger at a display of injustice and slightly arrogant and superior in his bearing. Despite this, the tenets of Hachiman’s code of honour also make him an extremely loyal ally to those who serve the Code of Thundera, namely the ThunderCats and their friends.
He has a great uncle named Nishida, who was also a samurai.