Katsuo is easily one of the most important people in Mercer's life (aside from his own parents, of course), and ever since the tiger started expanding his horizons by dabbling in various martial arts, his dragon friend has been an ever-constant presence in his life, not to mention the closest thing to a mentor that he has.

And when Mercer observed Katsuo in a spar with another man, using wing chun to great effect, he was impressed enough that he wanted to learn it for himself... and the dragon was more than happy to teach him, equal parts amazed and proud at how quickly his "student" was soaking up all this new knowledge.

Katsuo belongs to GaliosOnyxus
Art drawn by Lex Ferran