People saying that Fuyu is his daughter, but I bet imaginary bucks that she is his half-sister.
He GTFO from mama bear and went under the radar. Mama bear got crazy and got with the Yakuza, developed a relationship with the boss, got pregnant from him (Fuyu's martial arts prowess comes from him, and her blue eyes and desire to serve Matsu from Mama's) and took over the whole Yakuza Inc. after his death to look after her prodigal son.
Mama sends an email to Matsu AFTER Fuyu mentions her mom to him. Fuyu's mom tries to find a husband for her (and get her away from her man/son). The possessiveness with her daughter. The fact that Fuyu's mom want to "meet" with Matsu.
If the yakuza boss looks like Majima, I will have to think where ES goes into the gaming expanded universe.