The project is adapted from the popular 12 Shogakukan manga books Umizaru written by Yōichi Komori (小森陽一) and illustrated by Shūhō Satō from 1998 to 2001.

The film stars Hideaki Itō as Japan Coast Guard (JCG) rescue diver Senzaki Daisuke, and Kato Ai as his love interest Izawa Kanna.

Umizaru means "Sea Monkey"; this is a derogatory label slapped on the rescue diver trainees by local townsfolk of the city of Kure due to their excessive and uninhibited behaviour during off-hours.

Bored, and in order to be able to work at the forefront, he enters a 50-day training course for at the Japan Coast Guard Academy in Kure, Hiroshima, and officially starts his career.

In order to cheer him up, his former instructor deliberately arranges the Mishima Yuji team,[clarification needed] which is different compared from his own and are training rivals.