Burakon Joshi no Kekkon

The stage is Yokubari High School, an institution well-regarded across the country. Renowned for its leniency, the school strives for students' and teachers' comfort alike, valuing highly those who work and learn at their own pace.

One of Yokubari's students is Chiaki. Chiaki has had a crush on his childhood friend, Sakura, for ten years now. He's a late bloomer, however, so he hasn't been able to tell her all this time. Instead, he keeps getting picked on daily by Sakura's overprotective brother, Kaoru. Then, his sister Erika will step in to cheer him up. Seems like a peaceful routine, but...