Koshi is a Japanese man in his late 30s (he's 38 years old), he stands at 5'11 (180 cm), he has long black hair tied into a ponytail and wears glasses, he wears a black traditional Japanese Male Kimono, he's a Calm, relaxed and stoic and Emotionless man, he's always unbothered and unfazed and unimpressed all the time, he doesn't give a care in the world, of quite uncaring and foul-mouthed, he's a Jujutsu and Ninjutsu master, he's a former ninja and a Jujutsu practitioner