Kazuma can't stop masturbating with his mother Kana's underwear. His perverted mother Kana is excited by this and makes her panties smell even more, inducing him to masturbate. Unable to stop masturbating herself, Kana wanted to do something even more nasty. One day, she found an invitation to participate in a "room where you can't get out unless you ejaculate 10 times" project by the AV maker Das!, and secretly applied to participate without telling Kazuma...