My father is away on business, so I live with my mother, Yuka. I'm an introvert, and I worry about my mother, but last month I've become good friends with my classmate, Yuu, who moved in next door. We've become close enough to hang out every day, and I've even told Yuu that I'm starting a part-time job, which is prohibited. But Yuu prioritizes his adolescent sexual desire for his beautiful mother over keeping his secret. One day, when my mother says she'll be home by 7pm from her part-time job, I run out the front door worried about my mother, who still hasn't come home, and I hear moaning coming from Yuu's room...