ガンガン生射ち！お兄ちゃん、ボク、××しちゃうっ!!

The protagonist, Toshio Maekawa, is an unconventional third grader student who is in science major anywhere, and it is a virgin kun.
Such he was to work as a tutor during the summer vacation.

The other party to teach is the curious girl "Mami" who goes to a famous private school,
Somehow live in the neighborhood of Shun man's house, a cheerful girl called Sanae who calls him an older brother.
The place to teach is a resort apartment in midsummer owned by the father of "Mami". Besides, it is a study camp in the night.
At first, Toshio also seriously taught them to study,
If a man and a woman live under the same roof, it will be decided naturally.
The innocent girls at first were played with mere curiosity, but the act of the Shun was gradually escalated.

"I will do my best to beat you! ! "

Toshio who is attached to madness tries all sorts of sex and will do the best of fornication ....