The staff of Eiga Chiikawa: Ningyo no Shima no Himitsu (Chiikawa the Movie: The Secret of Mermaid Island), the first anime film adaptation of Nagano’s Chiikawa manga, revealed on Thursday the film will open in Japan on July 24. The staff also revealed a teaser video.
Image via Eiga Chiikawa Ningyo no Shima no Himitsu anime film’s website
©ナガノ / 2026「映画ちいかわ」製作委員会
Nagano is credited for the original story and is also writing the film’s script. Under Nagano’s supervision, Kei Oikawa (Uma Musume Pretty Derby 3 seasons, Hinamatsuri, My Teen Romantic Comedy SNAFU TOO!, My Teen Romantic Comedy SNAFU Climax) is directing the film at Cygames Pictures. QTORY inc. is managing the production, and TOHO is distributing the film.
The film is based on the manga’s arc posted on X (formerly Twitter) from March to November 2023, nicknamed the “Siren Arc” or “Island Arc.”
The film’s story begins with Chiikawa and Hachiware relaxing, when a rabbit with a flyer on its face suddenly appears. Hachiware looks at the flyer, which reads, “Invitation to a special island.” Lured by tempting promises including great rewards for simple hunts on the island and essentially free sweet and spicy dishes such as limited-edition island ramen and sweets, Chiikawa and friends decide to go to the island. Suspicious with the flyer, Rakko goes with them to the island. What awaits them when they arrive on the island?
Nagano originally started serializing the manga under the title Nanka Chiisakute Kawaii Yatsu on X (then Twitter) in January 2020.
The manga’s television anime premiered in April 2022, and it previously aired every Friday within Fuji TV’s morning news and entertainment program Mezamashi Terebi, before it began airing twice a week on Tuesdays and Fridays in April 2023. Sentai Filmworks licensed the anime, and is streaming it on HIDIVE with English subtitles.
Child actress Haruka Aoki (Liza in the Japanese dub of Mighty Express) voices the titular character Chiikawa as her first television anime voice acting role. Child actor Makoto Tanaka (Okko’s Inn) voices Hachiware. Ari Ozawa voices Usagi.
The anime’s new series premiered in July 2025. Before that, the anime had been rebroadcasting older “pivotal” episodes after its previous series ended regular airing of new episodes in April 2025.
Sources: Chiikawa film’s website, Comic Natalie
