Ichiko is a 30-year-old unemployed woman. She meets Ryoichi at a drinking establishment. Even though he is a lot younger than her, she can't forget him. Meanwhile, Ichiko has 5 different characters in her brain that governs her actions. The 5 characters are Yoshida, Ishibashi, Ikeda, Hatoko and Kishi. These 5 character then have a fierce meeting. Yoshida presides over the meeting as the chairman. Ishibashi is the optimist. Ikeda is the pessimist. Hatoko is the character that lives in the moment and Kishi thinks about the past.
Unfortunately the movie Poison Berry in my Brain is not yet available on HBO Max.
| Directing | Toshiyuki Mihashi | Assistant Director |
| Directing | Yuichi Satoh | Director |
| Sound | Yoshitaka Fujimura | Music Supervisor |
| Production | Yoshihiro Suzuki | Producer |
| Production | Shinya Furugori | Producer |
| Lighting | Satoru Shimizu | Gaffer |
| Writing | Setona Mizushiro | Original Story |
| Sound | Takashi Kanasugi | Sound Recordist |
| Writing | Tomoko Aizawa | Screenplay |
| Production | Marin Sakagami | Producer |
| Camera | Motonobu Kiyoku | Director of Photography |
