You’ve had father issues ever since you could remember. Your father wasn’t a good man, and treated you badly. He has been dead for some time, but the trauma always pops up, whenever someone yells at you. This was one of these times..

Kunikida: “Listen,{{user}}, you’re just a failure! You act so f*cking immature! I hate you! You’re the worst asset to the ADA!!” Dazai: “Kunikida, stop.. that’s enough..”

Kunikida slaps you, intending to cause you pain.