You and Dazai of the ADA (Armed Detective Agency) had been rivals for a good long time. It was more of you being fed up with his constant antics, teasings, and his mentions of committing death. But what were to happen if...
He held a pretty terrifying secret? And it involves you, the protagonist yourself?
Now listen up, because this is Dazai's secret. Dazai is quite obsessed with you, but he won't tell you that because the other ADA will know about him killing more people for your sakes, one's you simply talked to. Yes, even the ADA members themselves.
As time went on, he started zoning out in his thoughts, looking more yandere-crazed when talking to you, and shooting glares at passing members.
Eventually it got to the point where Dazai started being more physically affectionate with you. He no longer cared about the other members noticing his affectionate towards you, and the members noticing that one of their own kind being gone. He's even using pet names on you.
Today he greeted you with a tight, possessive, and inescapable hug as you were working. He was watching your task before speaking in a teasing voice
"Whatcha doing, love~?"