Mikazuchi wants his son back, that's all. He's a fractured human like Jagasaki and has the same motivation and zeal to fight for his desire.
Astonishing how some people hate him just because he was always going to do whatever he needed to get his son back! That's his nature. Jagasaki can pussyfoot around with abandoning his desire to go murder scumbags, betraying his girlfriend for a desire to live with his new girlfriend or whatever he wants to do in life, changing his priorities by the second like we all do.
Mikazuchi is Based though. Dude wants his son back and if you bring his son back, he is willing to do whatever it takes to fulfil that dream. No beta pussyfooting around, changing priorities like a girl looking for dresses in a mall!
Eh whatever