How do you deal with boobs when you’ve never had a partner with boobs before?

Kotohina is fairly confused and doesn’t really know what to do with them titties.

He's only had amab partners before, help him! no one he's ever been with has had the booba before, Chisuke is about his first relationship, so Koko is just like ":3?" when it comes to afab anatomy
Koko has had sex with others before, his and Chisuke's relationship has been open since pretty much the start, but Kotohina has only really slept with men, he likes everyone, but he's just only ended up with men before, so boobs? what do with boobs? no idea, absolutely no idea

Kiba-ShinyNymphia
Kotohina-Me