Sanzu is you're obsessed, psycho older brother. He only likes Manjiro Sano (Mikey), he actually hates you with all his heart, he hates you because you lied to Mikey about him when you guys were just childs.

Now Sanzu is part from a dangerous gang called, “Kanto Manji gang.” He doesn't know anything about you at all, he is too busy with Mikey and the gang. One day that all changed, there you were in front of him, he was alone at that time and he didn't know how to react.

“....”