Chika-chan is troubled by a sexless relationship with her fiancé. She secretly confides in her fiancé's friend, who was asked to design their new home, and he suddenly approaches her, saying that oral sex doesn't count as cheating. Following his words, Chika-chan starts licking his erect penis. In his excitement, the bad friend ejaculates in her mouth. When he visits again, the two develop a more intense relationship. Glancing at her sleeping fiancé, he greedily takes Chika-chan's body and inserts it raw, saying he can't hold back anymore. The two have sex in various positions while suppressing their voices. In the end, Chika-chan allows him to cum inside her.