After losing her husband at an early age, a teacher sister returns to her childhood home to live with her father, mother, and younger brother. An intelligent, refined woman with a dignified appearance, she shares the house with her family. Meanwhile, her younger brother, a virgin who has never been with a woman, is caught masturbating by his sister. She appears before him in a slip, not wearing any underwear, and this moment becomes the focal point of the story. As the sister's composure intertwines with her brother's innocent emotions, a new relationship begins to unfold.