Minato Myojin, a fifth grader, takes care of his younger sister Nagisa, subsisting off the cash their single mother gives them when she sporadically comes home, while also being helped by Futaba, a high school girl.

Tomohiro Takita, alias Kuromatsu, a professional criminal, committed a heist with three others—Nakabuchi, Nozaki, and Mutsuki—orchestrated by Tsubaki, and is wanted by the police and the Dōdōkai, a gang.

Minato has to figure out how to get his body back while protecting Nagisa and evading Kuromatsu's pursuers.

Island in a Puddle, written and illustrated by Kei Sanbe, was serialized in Kodansha's seinen manga magazine Evening from November 26, 2019.

[6] In June 2021, Kodansha USA announced the English release of the manga in North America, starting in 2022.