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I don’t know for sure, but maybe the Bakuman spinoff Otters 11? The synopsis I read mentions the main character being (in)famous for beating up criminals in the past. If that’s not it, then it’s also possible the OP was getting Ohba mixed up with his frequent illustrator Takeshi Obata. I’ve mixed them up a time or two myself and I know that Obata illustrated a one-shot (written by NISIOISIN) with an MC who tries not to let people see his face when he fights; that was Urooboe Uroboros, although I can’t remember if he actually fights with his back turned or not.
Edited by zequist
Found this at Badass Back:
e: Yeah looks like Urooboe Uroboros.
Edited by Amonimus