Human life started beneath the sea. However, some people preferred the surface and abandoned living underwater permanently. As a consequence, they were stripped of a protection which allowed them to breathe underwater. Over time, the rift between the people of the sea and of the surface widened. In the present-day, young sea people Hikari and Manaka, along with their childhood friends Chisaki and Kaname, are forced to leave the sea and attend a school on the surface. Teen melodrama and love triangles ensue, while a cataclysm looms in the distance.

This story is set across several mountain-isolated coastal fishing towns in Mie Prefecture called Hadasu, Atashika, and Nigishima. While the underwater sections are obviously fiction, some of the on-land locations are true-to-life. It is common for NagiAsu tourists to give a visit to Tennyo-za and try their curry. Inside there seem to be several posters, the manga, and various pilgrim mementos and guides. The nearby Onigajo coastal rock formation is a UNESCO World Heritage Site and is briefly featured.

Nagi no Asukara is an anime-original story written by Mari Okada and directed by Toshiya Shinohara for P.A. Works in 2013, and was also adapted to manga, including a 1-volume 4-koma spinoff.