That would be Akainu. During their attempts to escape, after Luffy had fallen unconscious following Ace's death, Jimbei was doing his damnedest to evade the Marine Admiral. A savage punch, penetrating Jimbei's body and ultimately hitting Luffy in the chest, was the cause of the scar.
posted sa loob ng isang taon na ang nakalipas
that's how he got the x?
neko_neesan
posted sa loob ng isang taon na ang nakalipas
Yep. Sort of an odd scar, I know, something to do with molten lava.
whiteflame55
posted sa loob ng isang taon na ang nakalipas