I think I'll go with Nozomu Itoshiki, even though he's a much less combat oriented character. He probably got into the animangaverse as a result of a botched suicide attempt. The man is impossible to kill, due to uncanny luck and extreme survival instincts; any time something would kill him, he miraculously escapes, suffering at the absolute maximum superficial injuries that put him into a short term coma.
(In the show, this required one of his students to sodomize his dog, brutally beat his head in with a baseball bat, then blow up his house around him with a massive quanitity of explosives. He was on his feet again within a week.)
Nozomu is very old-fashioned, and he'd interact interestinly with people from classical era Japan. He's also very very interested in rope work, for obvious reasons (hanging himself) and is implicitly into shibari. Some of his other hobbies include caligraphy, looking for good places to kill himself, and finding dramatic moments to shout "I AM IN DESPAIR!"
Here's the opening of the anime, to extablish the mood of the character: (he's the guy in the glasses and the formal kimono)Sayonara Zetsubou Sensei OP
And an AMV, of Itoshiki's various suicide attempts:Sayonara Zetsubou Sensei AMV - Suicide