In real life from my own experience, yes, some men's nipples are sensitive and causes arousal. Same for women, for some women it does nothing for them and for others their nipples are sensitive. People have different parts of their bodies that turn them on. In the Yaoi world, however, any part of the body is sensitive all the time. LOL!
Yaoi Logic: If your seme touches your body (anywhere at all) you are immediately turned on.
Tru dat
Das real talk
It depends on the person, really.
Not going to lie but my butt is sensitive, and my back. That's why I don't let people touch me. I'm not ticklish either, but for some reason from time to time I'm sensitive there. (o.O)
You'd be surprised how sensitive my nipples are and how dull my boyfriend's nipples are. It's so frustrating because for foreplay(we switch who's top and bottom), I usually target the nipples and pecs. Thing is, he doesn't feel ANYTHING from it. fjlwkdjfalwieuroiut. OTL Then there's me, who's just sensitive every-fucking-where... when I'm turned on, that is.
So to answer your pondering comment, yes. There are men out there who have sensitive nipples, but there also a good portion that don't.
And honestly, this is the first time I've heard of men with bras. It's like.. whatthefuckdidIjustread. LOL
ch.5: Sometimes I wonder if men's nipples in real life is as sensitive as in yaoi. The bra thing is weird but the sex is hot.