The Kose Private Cram School was an institution opened by the brother of our protagonist, Satoshi Kose, but after his brother’s untimely demise in a bike accident, Satoshi is left with no choice but to abandon the school. However, the school turns out to be full of girls who had a thing for his brother. While at a glance these girls only seem to attend to get into his brother’s pants, each of them have their own problems from issues to school, part-time jobs, and domestic troubles. The more time Satoshi spends with these girls, the more he comes to see just what kind of person his brother was. Though his brother’s death has left a hole in his heart, he works with these girls in an attempt to overcome both their problems and his and to move on with their lives.

From Summer Rain:

An incompetent high school student named Satoshi Kose suddenly loses his brother, Naoichi, in an accident. Thus now, he aims to save what's left of the fan girls whom his older brother, once an ultra-handsome guy, used to gather together. That is, through a little institution his brother once started - "The Kose Cram School"!