Three years ago, Kayoko Senba became the stepmother of Hiroyuki, and since then she has doted on him every day. However, as time passed and Hiroyuki began affectionately calling her "Mom," Kayoko gradually started developing romantic feelings toward him. One day, she discovered Hiroyuki masturbating while reading a porn magazine and realized he was still a virgin. Overcome with the urge to deflower him, she found herself torn between maternal love and newfound desire. Caught between these conflicting emotions, Kayoko resolved to personally guide her stepson's sexual awakening, determined to transform him with her own body while wishing for his growth.