The widespread popularity of Chiikawa in Japan and beyond is undeniable. Created by artist Nagano, this series has become a cultural sensation thanks to its unusual dark undertones that occasionally surface beneath its cute exterior. Starting as a web manga on X in January 2020, it has since expanded into an anime, manga volumes, various merchandise, and most recently, a theatrical film titled Chiikawa the Movie: The Secret of the Mermaid Island.
Even seven weeks after its premiere on July 24, the film continues to be a massive success, now Japan’s highest-grossing movie of the year. It earned over 1.415 billion yen from 928,000 ticket sales during its latest weekend (Source: LivedoorNews).
For those unfamiliar, Chiikawa the Movie: The Secret of the Mermaid Island is the first film adaptation of the web manga. Based on the manga’s “Siren Arc,” which was serialized online via X from March to November 2023, the story follows the main characters—Chiikawa, Hachiware, and Usagi—as they embark on an island journey. Their beach vacation takes a dark turn when they encounter the sea monster Siren and two mermaids.
According to Kogyo Tsushinsha, Chiikawa the Movie: The Secret of the Mermaid Island has accumulated 13.9 billion yen from 9.6 million admissions in just 45 days. It has now overtaken Detective Conan: Fallen Angel of the Highway’s 13.7 billion yen, ranking 23rd on Japan’s all-time box office chart as of September 6, ahead of Jujutsu Kaisen 0’s 13.89 billion yen.
On its debut day, the film sold out theaters nationwide early in the morning. TOHO Cinemas alone screened it 41 times in a single day at its Ikebukuro location. The film grossed 990 million yen on opening night alone, surpassing the 960 million yen earned by Detective Conan: The Million Dollar Pentagram in 2024. This marks an impressive start for Chiikawa the Movie.