Nagasarete Airantou revolves around Ikuto Tōhōin, the main protagonist, who ran away from home because of a fight with his father. Due to a life-long dream of wanting to board a ship, Ikuto decides to take a vacation on a cruise ship; the ship is suddenly hit by a huge storm, throwing Ikuto overboard. He wakes up the next day to discover he is on an uncharted island populated by girls. Ikuto finds himself to be extremely popular on the island, because no other men currently live there. As a result, nearly the entire island starts pressuring Ikuto to become their husband — all except a young girl named Suzu and her extremely old grandmother. Suzu's grandmother decides that Ikuto will live with Suzu for the time being, but Ikuto initially finds it difficult to adjust, especially with the entire island population after him night and day. Meanwhile, Suzu does her best to protect Ikuto from the masses. However, Ikuto still does not want to stay on the island, and soon after arriving, he attempts to leave by boat, but discovers the island is completely surrounded by whirlpools and tornadoes, eliminating escape by sea or air, thus impossible to leave. With no other choice, Ikuto starts to settle into life on the island.