Having lost her parents in childhood and grown up alone, Yui becomes the new English teacher at Eungbogo, where her father worked as a teacher 20 years ago. Settling into her old home where she lived with her parents as a child, Yui discovers a diary left by her father while cleaning the house, and vaguely recalls happy memories from her past. Following the diary's contents, Yui believes there might be someone who remembers her father and begins to inquire about traces of her parents, only to confront a shocking past...