A Sister Is All You Need

Itsuki Hashima lives life by only one rule: A sister is all you need. Well, that, AND writing creepy incest novels. What Itsuki doesn't know is that he already has the perfect little sister, it's just that sister happens to be his brother. But Itsuki, conforming to traditional gender norms, refuses to date his little brother. Instead, he tries to bang the nudist novelist who is much better at writing than him. There's also a pretty hot tax accountant in the show.