Living with her husband's parents, daughter-in-law Miyuki longs to conceive a baby, yet her marriage remains sexually dormant. One day, while cleaning the living room, she senses her stepfather's lewd gaze fixed on her backside. Startled and confused, Miyuki gradually realizes his intentions but finds herself unable to resist. In the living room, kitchen, stairway, bathroom—every corner of the household becomes a site for her first anal training. Her stepfather's anal torment intensifies, driving Miyuki to willingly offer her own anus. A forbidden story of anal initiation within the family, depicting inner turmoil and anal awakening.