My Little Sister Can't be My Girlfriend

Haruta, a first-year high school student is living with his little sister Fuyu, a third-year middle schoolgirl.

They are close siblings that one would call them a brocon and a siscon.

They share a same room, don’t mind being seen changing clothes with each other, and even go on dates on holidays.

But one day, they had an incident that made it impossible for them to continue their lives as siblings—