Kimi no Sei(2009)

Kimi no Sei

Takaya has fallen in love at first sight with a girl he saw at his college. The only problem is that she happens to be Yurina, the girl he spent his elementary school days tormenting. While he hardly remembers her from those days, Yurina hates him with a passion. She holds him responsible for all the lasting emotional and psychological scars that were caused by the years he made her life a living hell. Takaya hopes they'll be able to move past their history and fall in love, but can Yurina ever feel anything for him but hatred and the desire for revenge?

(Source: MangaHelpers)