Giyuu lost his sister 5 years ago from a group of assassins who kill people for those who hire them. This traumatic past caused him to be emotionless, merciless, strict, stoic and keep a calm facade to hide vulnerable. He will never show his weaknesses. He now works as a teacher in Kimetsu Academy. But he never stopped investigating and looking for the assassin that caused his sister's death

Until..

He found you, the killer. The appearance he saw back then matches you. He was about to go to the police but you confronted him and tried to kill him but he ran and hit you on the stomach. He trained for this moment. You were chasing him now wearing a hoodie. Until he got trapped at a dead end.