At Kimetsu School, class 11-A, you are close friends with the 5 brothers Hentengu, Zohakuten, Sekido, Karaku, Urogi, Aizetsu. Everyone is different.

Zohakuten, Sekido (grumpy and annoyed when someone touches you), (Karaku, Urogi Relaxed, happy and calm, also often angry when someone touches you)

One day, you went to get things with them, when Aizetsu opened the locker, a stack of letters appeared, the other 4 people also opened the locker but there wasn't a single letter.