A new mother, Ai, who remarried her father. Keisuke was frustrated by the familiar and mother-friendly love, but even for Ai, who had been abandoned as a child and lived alone for a long time, the first family he could have was not anxious. Mother-in-law who does not easily shorten the distance ... However, the charm of an adult with love gradually attracts Keisuke. Keisuke steals his underwear when he takes a shower, and Ai immediately notices that he goes to Keisuke with a bath towel.