Tsukimi Kurashita has wanted to be a princess ever since her youth. However, at 18 years old, she finds herself far from that dream. Instead, she has become a plain and shy girl who spends most of her time and money on her biggest obsession: jellyfish. Tsukimi lives with her fellow 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 abided by these rules until one evening—while rescuing a spotted jellyfish—she encounters a classy, princess-like woman. After allowing the girl to stay the night, Tsukimi is shocked to discover that the person is not a woman at all.