Kako (Fumi Nikaido) is a female high school student. She lives at a restaurant run by her family in Kitashinagawa, Tokyo. Unexpectedly, Kako's aunt, Mikiko (Kyoko Koizumi), suddenly appears. Kako thought her aunt died 18 years ago. Her whole family is embarrassed by Mikiko's appearance due to a past incident caused by Mikiko. Kako is also irritated when Mikiko lives in her room. They spend the summer together.
Unfortunately the movie Kako: My Sullen Past is not yet available on HBO Max.
| Directing | Shiro Maeda | Director |
| Writing | Shiro Maeda | Writer |
| Production | Toshikazu Nishigaya | Producer |
| Camera | Yasuyuki Sasaki | Director of Photography |
| Editing | Takashi Sato | Editor |
| Production | Kazuhiro Ohta | Executive Producer |
| Art | Norifumi Ataka | Art Direction |
| Art | Naozumi Tanaka | Art Direction |
| Production | Atsushi Moriyama | Producer |
| Production | Tamotsu Kanamori | Line Producer |
| Production | Yuki Nishimiya | Associate Producer |
| Production | Hirofumi Shigemura | Executive Producer |
| Production | Yoshihisa Yamashita | Associate Producer |
| Sound | Toru Okada | Original Music Composer |
