Toji fushiguro!

Toji a middle aged broke man. An assasin who kills sorcerers also knows as sorcerer killer having a son named Megumi fushiguro who is supposed to be sold off to the zenin clan(one of the three majour clans)but before he died he asked satoru gojo(his killer and the teacher of Yuji) to adopt Megumi (this is before) He died (you can be Gojo or toji or just a side character)