Chiikawa the Movie: The Secret of the Mermaid Island (2026)

Chiikawa the Movie: The Secret of the Mermaid Island (Japanese: 映画ちいかわ 人魚の島のひみつ) is a 2026 Japanese animated film directed by Kei Oikawa, based on the manga series Chiikawa by Nagano. It is the first film in the Chiikawa merchandise line. It was released in Japanese theatres by Toho on 24 July 2026.

Plot

Once upon a time, Siren, a legendary creature whose song could work magic for the plants, lived on an island with three mermaids. The islanders offered tributes to Siren, and she rewarded them with harvests by singing to crops. One day, Siren was playing with the mermaids and destroyed a boat with Hitoha and Futaba on board. When tending to Futaba, who was dying because of the incident, Hitoha recalled that anyone who ate a mermaid could gain eternal life. To save Futaba, Hitoha killed a mermaid and cooked it at home. When Futaba was revived by gaining eternal life after being fed a piece of mermaid by Hitoha, they were horrified at the thought of losing people and made Hitoha eat it as well. Hitoha and Futaba then discovered a battery slot on their bottoms and quickly understood the meaning of "eternal life" – when their "life" ran out, they could be "revived" by replacing the battery. They promised to keep the secret forever.

Meanwhile, furious at the death of one of her mermaids, Siren vowed to abduct and eat the islanders until the culprit was found. Since Hitoha and Futaba promised to keep their secret hidden, no one knew what had happened and hence the reason for Siren's aggression. In rage and vengeance, Siren abducted and ate the locals from time to time, putting the island in fear. Unable to bear the consequences, the islanders forbade anyone from contacting Siren and invited visitors from outside to help suppress Siren. In response, Siren also attacked visitors who tried to suppress her.

The film begins with Usagi, one of Chiikawa's friends, receiving an invitation letter to the island promising many rewards, including lots of delicacies. Many of the residents (recurrent characters of the series: Chiikawa, Hachiware, Usagi, Momonga, Furuhonya, and Rakko) then visit the island following the invitation. There, they enjoy the meals and celebrate. At night, Chiikawa, Hachiware and Usagi accidentally enter Siren's cave and learn her side of the story.

The next day, an islander announces the mission to suppress Siren, and the promise of a hundredfold reward is a lie, scaring off many island visitors. Leaving only Chiikawa and friends to defend. Later, Siren attacks and chases after the protagonists; Chiikawa eventually becomes the only one managing to escape. Chiikawa encounters Shimajirō, the owner of a restaurant in a remote area who makes clam soup and spicy curry rice. Chiikawa, with Shimajirō's help, frees all captives held by Siren. Convinced Siren would attack again, Rakko tries to conjure up a plan. Chiikawa, who ate Shimajirō's curry rice, suggests making a very spicy curry rice to disable Siren's singing attack.

Siren appears the next day. Chiikawa and friends force the spicy curry rice they prepared into her mouth, but Siren enjoyed the spiciness, and their plan foils. Later, Shimajirō offers the Carolina Reaper, saying that it was the only pepper that would be overly spicy for Siren. After forcing the Carolina Reaper-laced curry into her mouth, Siren begins writhing in pain. During her struggle, Siren accidentally notices the cover of the battery slot on Futaba. An agitated Siren acknowledges Hachiware's plea to stop attacking the islanders and retreats to the waters to ease the spiciness in her mouth.

After retreating, Chiikawa witnesses Hitoha replacing Futaba's battery. Adding to previously finding a mermaid scale in their home, Chiikawa figures out Hitoha and Futaba were the ones who killed and ate the mermaid. At the celebration of Siren's defeat, Chiikawa tries to talk to Hitoha and Futaba, but ultimately stays silent and returns to enjoying the party. The next day, Chiikawa and friends depart the island with gifts and cheers from the islanders. When leaving, Chiikawa takes the mermaid scale they had found at Hitoha's home. As the ship moves, the scale drifts back towards the island by wind. Seeing the scale flying off, Chiikawa starts chatting with friends.

In the post-credits scene, Hitoha and Futaba are revealed to have fled the island; they arrive on a new island and decide to reside in a cave. In the nearby ocean, Siren and her two remaining mermaids swim towards the island, closing in on the two immortal fugitives.

Cast

Production

The film is based on the manga's "Siren Arc" (Japanese: セイレーン編) or "Island Arc", which was serialized from March to November 2023. The screenplay was written by Nagano, credited as the original story. Under Nagano's supervision, Kei Oikawa of Cygames Pictures was selected as the director. Production companies QTORY, Cypic, Fuji Animation Studio and Toho are the film's distributors.

The opening and ending theme songs respectively titled "Kutsuzure" (くつずれ, lit. "Shoe Sore"), performed by Makoto Tanaka, "Tsukue Sasuru" (机さする, lit. "Desk Rubbing"), performed by Haruka Aoki are both written by Nagano.

The visual design of the Siren is based on an inu hariko (papier-mâché dog) for the upper body and a goldfish for the lower body. The inu hariko is a talisman believed to have originated in Nagoya's Atsuta Shrine, and is used to pray for fertility and safe childbirth, while the goldfish is a speciality product of Yatomi, Aichi Prefecture; This work features other elements evocative of Aichi, such as soy sauce and miso; the local preference for strongly flavoured dishes; curry reminiscent of CoCo Ichibanya, a company based in Aichi; Japanese manila clams, a seafood product for which Aichi boasts the highest catch volume in Japan; Kasugai City in Aichi is said to be the birthplace of Yao Bikuni, who ate mermaid meat; and Shiruko Sand used as bait to lure out the mermaid. CoCo Ichibanya sold katsu curry with manila clam toppingas, and mango lassi during the first period, and lemon squash during the second period in dedicated plastic cups as a collaborative product with this film with novelty item, the curry came with a sticker, while the drink came with a spoon rest, in both cases, the purchaser could not choose the design, from 16 July to 31 August.

"AA battery" in Japanese is usually shortened as tansan (単三), which is a homophone of the short name for carbonated beverages tansan (炭酸); It is also a soundalike of minor third (短三度, Tan-Sando), the music interval sung by the slain mermaid. Panasonic sold AA batteries in special packaging as a collaborative product with this film.

Ahead of the film's release, Seven-Eleven Japan sell collaborative deli items themed around the movie from 17 July to 3 August; These included rose fish nitsuke evocative to mermaid meat.

Release

It was released in Japanese theatres by Toho on 24 July 2026. The film was subsequently released in Taiwan, Hong Kong, and Southeast Asia with the former two receiving Mandarin and Cantonese dubs alongside the original Japanese soundtrack, respectively.

Reception

Since its release on 24 July 2026, the film has been the most-watched movie in its opening week in Japan, with 1,508,500 tickets sold and around 2.24 billion yen in revenue. As of 6 September, the film has grossed 13.8 billion yen from 9.6 million tickets sold. Internationally, the film has grossed NT$138 million in Taiwan and HK$22.4 million in Hong Kong as of 30 August.

The film involves bleak subjects such as revenge, murder, guilt and eternal torment despite the series' light-hearted nature. Many social media users described the film as a "horror movie" despite its perception as a family film. Audience reactions were noticing gloom, such as a comparison of a wake, some young children were seen leaving in tears.

Patrick St. Michel of The Japan Times compared the film to Crime and Punishment by Fyodor Dostoevsky. A review in The Yomiuri Shimbun praised the film as "approachable", with main characters who are easy to empathize with and a good artwork that can present the original manga world. Kanae Minato who famous Japanese writer of crime fiction and thrillers was say in her Instagram "'Kanae Minato' frequently appear at the reviews for 'Chiikawa the Movie: The Secret of the Mermaid Island'". After she show this film, she commented "'A bad aftertaste' ≠ 'I like other people's misfortune', 'A bad aftertaste' = 'It makes me think about right and wrong and righteousness'; That's how I see it, so I have no qualms about describing a work with a bad aftertaste as 'interesting'." "I sensed the kindness of the original creator, Nagano, in the fact that Hitoha and Futaba’s faces were left undrawn; it struck me as a work that deserves more than just a discussion about the lingering impression it leaves".

Its film content ratings in airing locations are:

References

External links

Official website (in Japanese)

Chiikawa the Movie: The Secret of the Mermaid Island at IMDb

Chiikawa the Movie: The Secret of the Mermaid Island at Rotten Tomatoes

Chiikawa the Movie: The Secret of the Mermaid Island (film) at Anime News Network's encyclopedia