Onii-chan Asobo

Koichi Akiyama, an ordinary 22-year-old game developer, has been living a boring life until one day his younger sister Ai paid him a visit.
Soon after Ai moves in with Koichi, she claims that she wants to become a game developer too, so her brother has to teach her everything he knows.
The only problem is that Ai wants to create Hentai games, which puts Koichi in a dubious position.
From now on these two need to learn how to work together and explore all the difficulties of writing Hentai stories.