Heaven's Lost Property (2009)

There's no explicit nudity shown at anytime during this series.

The male protagonist is often naked, but his genitals are obscured.

The girls wear a lot of revealing clothing, and there are many shots of naked girls in locker rooms, swimming pools, bathrooms, and changing rooms. However, their nipples and/or genitalia are always discreetly covered either by hands or cloth, or else it is a back-shot only. The occasional buttock is shown, but these shots are very brief, 1-2 seconds at most.

The male protagonist's main obsession is trying to get peeks at naked girls, including up their skirts, using a spyglass, and sneaking into girls' bathrooms and locker rooms.

References to erections (including an accidental "poking") and girls' underwear (or lack thereof) are prevalent.

One episode shows a boy "face-planting" in a woman's crotch, although this is purely accidental and she is wearing underwear at the time.

In season two, Tomoki disguises himself as a girl, and asks to measure Astraea's breasts and butt. (S)He then falls into her breasts and butts, pretending it was an accident.

Some characters get bloody noses during emotional episodes.

A girl often beats up her friend with vicious karate chops when she is mad or upset at him, with resulting injuries shown.

Later in the second series, the main villain is seen repeatedly beating a woman.

Most of the series stays away from frightening/intense scenes, but there are a few, like gun fights and monsters.