Aveva 4 is a good doujin. It's by a circle called St. Rio, that also managed to do a very good seriesmini franchise of Love Hina doujins called Love Dasi.

It stars with Takako being sexually solicited, she quickly gets stripped to reveal some hot S and M uniform, and Hiromu goes to town on her with a dildo.

Then he takes her from behind in some hot doggy style. Then they pretty much continue having rough sex for the rest of the scene, there's not much position changing.

Then there's some Chi on Chitose action. Chi starts working on Chitose with a dildo while Hideki watches. Then Hideki does Chitose from behind, while Chi starts in on herself with a dildo.

St. Rio has had good art in all their doujin. This one is no expection, we get two under-appreciated side characters, and we get to see a lot of nice big busted images. We get to see some nice views and scenes.

Honestly, I like Aveva infinitely more than Love Dasi. Perhaps its just that I'm generally not a fan of forced group sex scenes because I feel it lets the artist be lazy, or perhaps its the material.

Regardless, the Aveva series, unlike the Love Dasi series, focuses on pairings between characters actually in the show. Aveva 4, in particular, depicts nearly all of the characters in an accurate-to-the-source way, but still manages to be hot hot hot. The art is very well done, if simple, and the censorship isn't as horrific as one might expect out of a St. Rio work.

I should note, though, that Chitose changes radically in her depiction throughout the Aveva series. If you're looking for consistent character models, go elsewhere. But if you're looking for well-drawn Chobits doujin, look no further.