I was rereading earlier chapters and noticed Knight-girl and the Komi Guard back in the first cultural festival arc. https://mangadex.org/chapter/33910/9
(she's also part of the "class masochists")
Guy I went to school with could do that. He loved showing it off to the girls. No sooner did he finish and show it to them, they were astounded by how skillful he was with his tongue. And he was always willing to show them just how skillful he was, too.