Tsukimi Kurashita is a twenty-year-old aspiring illustrator who has retreated from the world. Withdrawn and socially terrified, her only passion is for jellyfish, a love inherited from her late mother who once compared their floating forms to princess dresses. Tsukimi lives in Amamizukan, an old apartment building in Tokyo with a strict no-men-allowed policy that houses a close-knit community of socially awkward otaku women who call themselves the Sisters. Each Sister has her own obsessive interest: Chieko collects traditional Japanese dolls, Mayaya is consumed by the Chinese epic Romance of the Three Kingdoms, Banba is a train enthusiast, and Jiji has a fixation on older men.

Tsukimi’s secluded life is upended when she rushes to save a pet jellyfish in a local shop and receives unexpected help from a glamorous, stylish woman. She brings this fashionable stranger back to the male-free Amamizukan, only to discover that her new ally is not a woman at all but Kuranosuke Koibuchi, the handsome and wealthy son of a powerful politician. Kuranosuke cross-dresses both as an act of rebellion against his father’s expectations and to express his love for fashion, which he hopes to pursue as a career. To keep his secret and remain welcome among the man-fearing Sisters, he adopts the alias Kurako.

A major threat soon emerges. A real estate developer named Shoko Inari plans to demolish Amamizukan and replace it with a luxury hotel. Kuranosuke, who has grown genuinely fond of Tsukimi and her eccentric housemates, refuses to let this happen. He discovers that Tsukimi carries a lifelong dream of wearing a wedding dress that looks like a jellyfish, a promise her mother once made to her. Believing in her hidden talent, Kuranosuke convinces Tsukimi that she can design and create a jellyfish-inspired fashion line. This project, he argues, could raise enough money to save their home from demolition.

As Tsukimi reluctantly steps into the terrifying world of fashion and business, she also finds herself caught in an awkward romantic triangle. Kuranosuke’s older half-brother, Shu, a serious and gentle political secretary who suffers from a phobia of women, sees Tsukimi dressed up during a makeover and falls for her, though he does not recognize her in her normal, frumpy state. Over ten episodes, the shy jellyfish lover must navigate her growing feelings for both brothers while pushing past her own insecurities. With the help of Kuranosuke’s relentless encouragement and the reluctant teamwork of the other Sisters, Tsukimi begins to transform from a terrified recluse into a young woman capable of fighting for her home and her dreams.