Aneimo, also called Square Sisters, is a two episode OVA released in 2008. Each episode is 30 minutes long and it take its source from a visual novel. Once I find info on that novel I’ll post it here.
Takumi lives next to Mizuki and Satsuki’s house. They have been good friends since they were kids, going shopping and skiing together. One day, Kazuyoshi, Takumi’s father, brings two girls, Saori and Yui, back to their house, and accepts them as new family members. At first, he is confused, but gradually becomes closer to them…
The story of Aneimo (which despite it’s name has no incest) is a fairly standard “harem-romance” story (at least for a hentai). The main character Takumi’s father has just let two teenage sisters stay at their house and now Takumi is supposed to consider them his step-sisters (I mentioned his dad but you never really see him thankfully). Later, Takumi happens to see the older sister, Saori, masturbating in her bedroom (with the door ajar, of course, because hentai girls are horrible at masturbating secretly). This causes Takumi to fall in love with her, but along the way he has sex with the other three named female characters. Still I do enjoy the fact that there is actual romance in Aneimo unlike many hentai. The sex scenes are all different in some way and each have their own appeal and are definitely the highlight of this show (as they should be in a hentai).
The story was definitely a modern(realistic) romance. Not just with one girl but three others. There was step incest. Although i was surprised with four girls that the main character got not one scene of a threesome or more. Not even a naked mishap such as one girl undresses ready to rock his world at the same time as another. Something else worth mentioning maybe it was just my copy but the LIGHT THE LIGHT! why so bright? yes, i know the sun is bright but no need for that especially in the sex scenes. I might need to go check my eyes later.