Eiga Chiikawa: Ningyo no Shima no Himitsu (Chiikawa the Movie: The Secret of Mermaid Island) has expanded its cast roster just days before its theatrical debut. Momoka Terasawa and Sayumi Suzushiro have been tapped to voice the characters Hitoha and Futaba, two islanders the protagonists encounter during their mysterious voyage.
The film adapts the popular "Siren Arc" from Nagano’s original manga, which follows Chiikawa, Hachiware, and Usagi as they are lured to a remote island by promises of easy rewards and exotic cuisine. Suspicious of the invitation, the character Rakko joins the group to investigate the island's true nature. The film’s screenplay is written by series creator Nagano, who is working closely with director Kei Oikawa to bring the story to the big screen at Cygames Pictures.
Production is being managed by QTORY inc. with distribution handled by TOHO. The project features a veteran production team, including character designer Tomoko Tsuji and music composers Shūgo Tokumaru and Chikara Uemizutaru. Makoto Tanaka, the voice of Hachiware in the television series, is also confirmed to perform the film's opening theme, "Kutsuzure."
This film marks a major expansion for the Chiikawa franchise, which has maintained a consistent presence on Japanese television since April 2022. While the TV series—currently licensed by Sentai Filmworks and available on HIDIVE—continues to air as part of Fuji TV’s Mezamashi Terebi, this theatrical release represents the first feature-length adaptation of the series.
