Recently, Yumi's daughter Miku has started wearing makeup and has been absent from school without permission. Her husband is away on a business trip and she can't rely on him, so her mother Yumi tracks down Miku's friend and visits her house, a girl named Sora. Sora has a bad reputation at school and is a typical delinquent. Yumi is told by Sora that she will tell the school that Miku has been shoplifting, so she can't resist and ends up letting Sora play with her body. After that, whenever Sora comes to visit the house, she starts asking for lesbian sex with Yumi when Miku isn't looking...