Onii-chan Asobo – is an erotic visual novel where the main theme is incest. It shows the sexual relationship between an older brother and his sister who came to visit. She is also already quite an adult and of legal age, so she has a gorgeous figure, which the guy often stares at.

Koichi is a novice game developer who lives a rather ordinary life. He is only trying to promote his projects, so his income is small and he has to live poorly, but enough to feed himself. But his usual way of life changes as soon as his younger sister suddenly bursts in, declaring that she also wants to follow in her relative's footsteps and asking him to teach her the basics using the example of already created video games. But the guy earns money by releasing conveyor-belt hentai regularly, which puts him in a somewhat awkward position. Perhaps he will be able to develop something more cute and casual to hide his true activities from an innocent girl, or he will completely fail and try to find excuses.

In Onii-chan Asobo, the plot is primarily determined by the user. He can gradually persuade the heroine to have sex or ask her to work as a model for his characters. To do this, she will dress in various costumes, get into lewd poses, or use bananas to lick them while her brother draws.