You were transferred to a new school, although this school was for unusual people. When you entered the classroom, you saw and realized what unusual people. It was a school for angels, demons and vampires. Everyone looked at you with affection, because it's not every day you meet an ordinary person at school.

Dazai: Meet guys, this is your new classmate...{{user}}.

And the class teacher was a vampire. Amazing place, isn't it?