Satomi works at an art museum until an envelope arrives, containing a mysterious key. It leads to an unknown room once belonging to her late father, who died alone a month earlier. Drawn by this small object, she retraces his final days: a man seemingly left behind by society, yet sustained by a quiet devotion to words, the art of tea, and subtle beauty. Through the traces of his solitude, Satomi slowly discovers the quiet grace of the world he inhabited.