Yukana was once the private tutor who dramatically changed Kaya's life. Through her seductive tutoring methods, Kaya achieved the miracle of getting accepted into medical school. A year has passed since then, and Yukana has married Kaya's father, beginning a new chapter in her life. Now, she returns once more before Kaya—not merely as a teacher, but as a stepmother determined to fulfill her maternal duties. Their relationship evolves beyond past bonds, taking on a new, forbidden form.