Sai

Misa's father, and Karasu's right-hand man. Sai is Karasu's most trusted and capable employee, responsible for overseeing his most lucrative business ventures, despite always working in the shadows. Unrivaled in what he does, Sai is a ruthless killer who feels no remorse; those who get on his bad side seldom live long enough to realize it. The only things more important to Sai than his work are his daughter's well-being and happiness. [Taken from official website]