- Nogizaka46's Yuki Yoda (Mob Psycho 100) as Chisa Kotegawa, Iori's cousin
- Aya Asahina (Cheer☆Dan) as Nanaka Kotegawa, Chisa's sister who has a sister complex
- Yuka Ogura (The Werewolf Game) as Azusa Hamaoka, a girl who gets along easily with her friends
- Ren Ishikawa (Tokyo Tarareba Girls) as a gyaru who has fulfilled her college debut
- Masahiro Takashima (Godzilla vs. Destoroyah, Kingdom) as the Kotegawa sisters' father
Based on Kenji Inoue and Kimitaka Yoshioka's booze-fueled diving comedy manga of the same name, the film is directed by Tsutomu Hanabusa (live-action Kakegurui) with the production company "THE FOOL". Grand Blue Dreaming is set for a May 29th release in Japan. Warner Bros. Japan is distributing the film.
[Source: Anime News Network]