Renai Shinjuu summary:

When they were 12 years old, Runa and Ren were very much in love, but Runa’s mother was against it – they were far too young. Ren did the unthinkable, tried to have the two of them commit suicide together rather than be apart. The suicide was a failure but both kids were hospitalized with serious injuries. It didn’t break them apart but eventually Runa’s parents were able to separate them.Several years pass and Runa has moved on with a new boyfriend named Shou when Ren suddenly shows up attending the same high school, very sexy and still in love with her, and suddenly her life is very complicated…