It’s okay. I got the answer from twitter. In the novel, it was stated :
"I don't... like being touched there..!". It wasn't...as if he'd never been touched there, but he couldn't stand the idea of being so utterly open and defenseless beneath someone else.
"..Wait, don't tell me this is-your first time?"
"...NO COMMENT." He didn't want Kirishima getting any ideas in his head about Yokozawa's past—and even less so did he intend on dredging up Kirishima's own himself. While it would be a lie to say he wasn't at least curious, he knew full well the powerful force his jealousy could become.
So clearly, that Takano indeed the top.
He is
After so many years, I came to read them again. Now that I read, does that means Takano was the top when he slept with Yokozawa ?