Eiga Chiikawa: Ningyo no Shima no Himitsu (Chiikawa the Movie: The Secret of Mermaid Island) has become the year's biggest film in Japan, raking in 13.9 billion yen (approximately $89.1 million USD) at the box office. The milestone came during its seventh weekend of release, when it sold 928,000 tickets and earned 1.415 billion yen alone.

The film's total now surpasses Detective Conan: Highway no Datenshi, the Detective Conan franchise's 29th entry, which had held the 2026 top spot with 13.7 billion yen. Chiikawa's achievement also places it 23rd on Japan's all-time box office rankings, leapfrogging several major releases including Jujutsu Kaisen 0 and earlier Detective Conan films.

Since opening on July 24, the film has sold 9.6 million tickets total. It debuted at number one and showed no signs of slowing down, earning 990 million yen on its opening day alone and 2.24 billion yen in its first three days.

Based on the manga's "Siren Arc" (the storyline posted to X from March to November 2023), the film follows Chiikawa and Hachiware as they're lured to a mysterious island by promises of rewards, hunts, and exclusive food like limited-edition island ramen. Suspicious Rakko tags along to investigate. Creator Nagano handled both the original story and the film's script, overseeing production directly.

The film continues to draw crowds with fresh offerings. 4DX screenings launched during the seventh weekend, and the studio announced a fourth wave of charm figure giveaways. Upcoming special events include one-day-only cheering screenings on September 11 and penlight screenings on September 23.

The success reflects Chiikawa's broader popularity—the manga, which debuted on X, has built a devoted fanbase drawn to its cute character designs and lighthearted humor that masks darker undertones. This first film adaptation proves that appeal translates powerfully to cinema.