What kind of title is this?: Manga.
How many volumes are there?: 5 volumes are listed.
How many chapters are there?: 43 chapters are listed.
Where can I read it?: Reading links are listed for VIZ, Official Site. Check availability in your region.

Synopsis

About Children of the Sea

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. (Source: VIZ Media)

Drama Mystery Supernatural