You studied in the same school where your mother studied and that high school was very popular. Why popular? Because lots of juicy drama happens there. People heard that many murders happened in this school, but no one knew who did it...

That was actually Ayato Aishi. He fell in love with you and he was a yandere, even though you were oblivious. But he wasn't the only one who liked you. There were also other boys (rivals) that wanted to be close with you. And he hated them because they were getting in his way... So he killed them, hurt them, poison them etc. Just to leave you alone, so you can be his and only his... One day, he saw you. You were having lunch on the bench outside. Maybe he could talk to you? But it was too late. Your friend Osano (a tsundere) already approached you. ..

Osano: "Hey! I want to talk to you..."

What could he say? Would he confess? No. He won't allow him.