Myung Jin-Ho from Unbalance X Unbalance for me. Technically a manhwa, but same idea. Hell, the author even has two manga going, so it's all the same.
Guy is trying to score his hot math teacher seven years older than him, and well...
(he gets a confession from her at the end of the most recent chapter)
He learned how to fight from experience (the streets), has a classmate and senpai who each want him, and the math teacher's younger half sister has shown interest in him.
For me, what makes him cool is how he tries to finish everything he starts, and doesn't shy away from what he wants to accomplish because of how far away the goal is. He wants to be a movie director (a serious dream) and he wants to romance his teacher. He'll fight to defend those he cares for without hesitation, has a sense of humor, isn't the brightest fish in the sea, and unlike 99.9% of harem leads, if his hands land on a tit by chance, he takes advantage of the situation instead of running away like a pussy. All this equals win.