Idol☆Sister

Stories about Idol's intimate relationships with their manager/producer, vanilla and wholesome are the genre served. 

Don't worry the word bitch is just used here to describe a person who loves sex, BUT only with the brother that she loves, that's right nothing more here than pure, unadulterated, vanilla wincest (plus one or two girls), good animation in both of them and great art, it's really beautiful when that happens, the little sister in both is blonde (which is a pretty common trope with little sisters). In Imouto Bitch there's two episodes for two imoutos, in Katekano there's besides the imouto, two another girls who aren't blood related, but it's still a nice addition. Enjoy. 

Take Oreimo and make it a hentai, yes, there's doujinshis, but here's an anime pretty similar to that, in the beginning two of the females start acting pretty tsun (like Oreimo) to later have passionate sex, and of course there's a little sister in all of this, who is blonde (see, like in Oreimo), if you have a thing for wincest you definitely will like it and even if you don't there's the other two girls to chose from or just the idol part of it all (which also kinda was in Oreino, I mean she was a model and whatnot). 

Both have incest and neither one has hardcore stuff in it. All of it is tame and good. 

They both are very tame shows. Both feature multiple girls and 1 guy and they all have consensual sex and no extreme kinky fetishes.