Kitamori Asako (60 years old) is now widowed and lives with her son and his wife in a peaceful region of the Kanto area. Her grandson Takumi (22 years old) is a university student living alone in Tokyo. Taking advantage of his break, Takumi decides to get his driver's license and returns home after a long time. However, his parents (Takumi's parents) are away on a trip, leaving Asako and Takumi alone together. Due to a small trigger, a forbidden relationship begins between the grandson and his grandmother...
