"Don't worry about who doesn't know one plus one equals two. You just need to know..." Perhaps because he had dealt with Katsura Kotaro plenty of times, Sogo Doma was quite good at handling airheads like them. That was, don't expect them to understand what you were implying—just say whatever needed to be said outright:
"People can get silenced just for learning that one plus one equals two. Never mind that I know so many people's secrets. I just feel that if I'm the only one who knows those secrets, then one day I might get taken out by the people who own them..."
Everyone: -_-
If they could take him out, they really would have liked to. Ahem... Damn it, if he knew it was dangerous, then he shouldn't go digging into other people's secrets!
"So..." As everyone continued grumbling inwardly, Sogo Doma went on, "for my own safety, as long as I reveal every secret I know, then no one has any reason to target me. For example, Eriri doesn't want people knowing she likes otaku stuff, and I just happen to know that she's an otaku...
"If I don't say it, she might overthink things. She might even worry that I'll use it to threaten her. How did that saying go again? You can't test the human heart. The more she thinks about it, the angrier and more scared she might get—under those circumstances, she might just decide to go all the way and kill me..."
Everyone: "..."
It made so much sense that they were left speechless.
"But after I say it out loud..." Seeing that everyone seemed to have "understood," Sogo Doma continued, "no matter how worried Eriri is about it getting out, no matter how scared she is, she won't start thinking about going