The protagonist "Daiki Shimokawa" moved away from the countryside and started living by himself to attend a university in the city. He works part-time jobs every day in order to earn money to pay for his tuition and living expenses.

One day, there's this gyaru who's one of his juniors at work, and she's looking for a place to hang out with her friend. They decide to stay the night at his place.

Just when he thought the girls were fast asleep after they tired themselves out playing games, the gyaru finds out he's got a boner in his pants. She got turned on by this, and proceeds to indulge herself with his body, but...

(Source: DLsite)