Houkago Nyannyan

Episode 1 is separated into two stories.
The first story is shorter but I think it's better, it's very adorable.

The first story is about schoolmates at school.
The second is about a boy spending the night at his girlfriends house while her parents are away.

This hentai is censored.

This is a 19 minute hentai with an odd flash-animation kind of style which at least gives it something unique in that aspect as most of the show is just average (not bad, not great) in every way. It follows two girls who know nothing about sex (or even what a penis does) who get involved in a sexual relationship with a guy because of their curiosity about sex.

The first story is about two high school students. The girl has the guy masturbate in front of her to see what happens, and it eventually leads to them having sex.
The second story is about a ... high school couple who are spending the week at the girl's house while her parents are away. They start out wary about having sex a lot but eventually end up doing it many times throughout the day.

As for the art, both girls look almost identical with just slightly different hair colors (one is brown, the other is a little reddish). The guys are basically the same way but who cares about them. It's purely vanilla the whole time, so all of the sex scenes are just different normal positions that you could find in a lot of other hentai. Just some "sneak attack from behind while washing dishes," "sex on top of a desk," and other kinds of things like that. The music is also barely noticeable and nothing impressive, but the two girls do have good voice actresses at least which makes for some pleasurable moaning and other sounds.

Houkago Nyannyan (which despite the name has nothing to do with catgirls) is an average hentai with a peculiar animation style that may turn some people off. I got used to it pretty quickly and had no problem with it, though, so I would still recommend that you give this one a watch. It does have a sequel if you dislike single episode hentai which is called "Lovely Days," but I have not seen that yet so I can't say how good that is.