It's heavily implied Akio had sex with female and male students. Akio in general sexually manipulates people to get what he wanted

It's implied Akio slept with uthena

It is implied many times that a girl has sex with her older brother. This is shown in quite a few episodes.

A girl is shown naked a few times, however, her long hair usually covers her breasts and genital area.

Various characters are slapped in the face over the duration of the series.

A man is slashed with a sword across his chest. There is no blood and you can't see the cut on his body.

There is rare use of some mild/moderate profanity in the series; one memorable use of "son of a bitch" in episode 23, "damn", "hell". (English dub)

None.