Mai is a wife who lives with her husband, much older than her. She starts working part-time because she feels depressed at home. In reality, she is working as a parts model at an atelier for a man who likes her beautiful, plump lips. She cannot refuse the man who is aggressively approaching her lips, wanting to take some good photos, and the massage progresses to a kiss. With each visit, she is trained to enjoy pleasure through her lips. "Hmm, something's different than usual...?" Her husband does not know. A lewd relationship that cannot be told even if her mouth is torn apart.