Shingin Harada forced Mariko Yashida to marry another criminal boss who beat her nearly to death. When Wolverine found out about this he confronted Shingin. Shingin then had Wolverine poisoned, temporarilly greatly weakening him so that he could beat and humiliate the superhuman mutant in a duel with wooden swords in front of Mariko Yashida.
Shingin used his expert knowledge of human anatomy to secretly attack Wolverine's nerve endings in such a way so as to make the duel life threatening. However, as Mariko did not know this when Wolverine attempted to use his claws against Shingen to save his own life it appeared to Mariko that he was cheating in the duel. Mariko did not know that Wolverine's body had been saturated with enough lethal poison to kill several dozen ordinary men, or that Shingen was the one who was actually cheating in the duel. This had the effect of disgracing Wolverine in front of his lover, which was the design of Shingen.
Wolverine then completley destroyed the Yashida criminal empire. When Wolverine confronted Shingin a second time, Shingin did not survive. Mariko Yashida and Wolverine however, did not marry for Mariko believed her father and his criminal ties had dishonored her and she was not worthy of him.