Nothing. The show is set in highschool so some girls fawn over boys (and vice versa), but nothing inappropriate is said. Show is very wholesome.

Mitsumi's aunt is trans. This is first implied after a background character whispers, "is that a man?". Other characters don't question it and seem accepting.

In Japanese subtitles: Infrequent mild language. Uses of h*ll, a**, d*mn, and a few religious exclamations. It's implied a character gives the middle finger but it's obscured by a person's hand so you can't see it.