Harama Seiichi became the manager of Hanajima, one of the Otomehara Islands inhabited solely by women, and lived surrounded by islanders, including the Kowakame family, a mother and daughter duo with ample bosoms.

While blessed with many children and living fulfilling daily lives, he met the heartbroken Mera Reika.

"Nyōninjima" is an island that brings happiness to women. Unable to leave Reika, who exuded a somewhat tired aura, he invited her to Hanajima to refresh herself.

Reika was extremely wary of Seiichi, who had impregnated all the women on the island, but the peaceful island life and the smiles of the islanders living there gradually won her over, and she slowly opened up.

Reika slowly shed her former self, and seeing the women happily having sex with Seiichi, her values began to change.

She resolved that she too could find the "happiness" she had long given up on here, and Seiichi accepted Reika, who, though unaccustomed, desperately invited him.