Tsukimi Kurashita has longed to be a princess since her youth. Yet, at 18, she is far from that dream. Instead, she has turned into a plain and shy girl who devotes most of her time and money to her greatest obsession: jellyfish. Tsukimi resides with other niche hobbyists in the all-female Amamizukan apartment complex, where the two most important rules are to avoid stylish people and men. Tsukimi has always followed these rules until one evening—while rescuing a spotted jellyfish—she meets a classy, princess-like woman. After letting the girl stay the night, Tsukimi is shocked to discover that the person is not a woman at all.