The official website for Studio 4°C 's anime film of Daisuke Igarashi 's Children of the Sea ( Kaijū no Kodomo ) manga began streaming a music video for Kenshi Yonezu 's theme song "Umi no Yūrei" (Ghost of the Sea) on Tuesday. The video previews the whole song, and shows clips from the film.

Yonezu wrote and performs the song. The newly written song is Yonezu's first theme for a film. Yonezu and Igarashi have been friends since Yonezu contributed the official image song for Igarashi's "Louvre No. 9 — Manga, the 9th Art" museum exhibition in France in 2016.

Viz Media published the manga in English, and it describes the story:

When Ruka was younger, she saw a ghost in the water at the aquarium where her dad works. Now she feels drawn toward the aquarium and the two mysterious boys she meets there, Umi and Sora. They were raised by dugongs and hear the same strange calls from the sea as she does. Ruka's dad and the other adults who work at the aquarium are only distantly aware of what the children are experiencing as they get caught up in the mystery of the worldwide disappearance of the oceans' fish.

The main cast includes, Hiiro Ishibashi as Umi (left in image below) and Mana Ashida as Ruka Azumi (center). Airu Kubozuka was initially announced to play Sora (right). However, he dropped out of the role since he had trouble with his voice changing due to puberty.

Other cast members include (left to right in image above):

min Tanaka as Jim, a former friend of Anglade and a marine biologist who now takes care of Umi and Sora

as Jim, a former friend of Anglade and a marine biologist who now takes care of Umi and Sora Seishū Uragami as Sora (cast after Kubozuka dropped out)

as Sora (cast after Kubozuka dropped out) Win Morisaki as Anglade, a genius marine biologist who pursues the mystery surrounding Umi and Sora

The film also stars, from left to right in the image below, Sumiko Fuji as Dede (a mysterious figure who watches over Umi and Sora), Goro Inagaki as Masaaki Azumi (Ruka's father who works at an aquarium), Yū Aoi as Kanako Azumi (Ruka's mother, whose relationship with both Riku and Masaaki is strained), and Tōru Watanabe as Sensei (the coach in charge of Ruka's hand-ball team).

Joe Hisaishi of Studio Ghibli fame is composing the music for the film. Ayumu Watanabe ( Space Brothers , After the Rain ) is directing, and Kenichi Konishi ( Tokyo Godfathers , The Tale of the Princess Kaguya ) is the animation director and character designer.

The film will open in Japan on June 7. GKIDS will screen the film theatrically in North America in Japanese and English in 2019. The film will screen at the Annecy International Animation Film Festival in June this year in the festival's new Contrechamp category.

Igarashi launched the manga in Shogakukan 's IKKI magazine in 2007, and ended it in 2011. Shogakukan published five compiled book volumes for the manga, and Viz Media published all five volumes in English. The manga earned nominations and awards of excellence from the 38th Japan Cartoonist Awards, the American Library Association's Young Adult Library Services Association, the School Library Journal , and the 13th Japan Media Arts Festival Awards.