Byakuyakou

Ryouji Kirihara and Yukiko Karasawa are a little couple in their 6th year oh elementary school. They got in common, that they are not much loved by their parents, his mother got a affair, his father is never at home and her single-mother is an alcoholic. Their parents disallow them to see each other after Ryoujis father saw them together. When Ryouji finds out his father is taking nude photos of Yukiho and is paying her mother for that he kills his father. Yukiho is relieved, but Ryouji is starting to get conserned about what he did. To avert suspicion Yukiho tries to put on a scene looking like her mother commited suicide to foist the murder to her. Her mother dies, too.
Now Yukiho and Ryouji can't be a couple anymore because he is the son of the victim and she is the daughter of the murderer. They decide to split up untill dust settles over this situation and meet again seven years later. But they are kept track of by detective Junzou Sasagaki...