At the prestigious Ouran Academy in Bunkyo, Tokyo, a school for the children of the ultra-wealthy, scholarship student Haruhi Fujioka is a bright but practical outsider. Looking for a quiet place to study, she stumbles into the abandoned Third Music Room, the extravagant clubhouse for the school’s most popular and eccentric group: the Host Club. This all-male club, led by the princely yet melodramatic Tamaki Suoh, exists to entertain the school's female students with tea, pastries, and charming conversation.

During her first encounter with the hosts, Haruhi accidentally destroys an antique vase valued at eight million yen. To repay this massive debt, she is forced to become the club’s errand boy. Due to her short hair and gender-neutral appearance, the hosts initially mistake her for a male student. Even after they discover she is a girl, they recognize her natural ability to connect with people and promote her to a full-fledged host. Keeping her true gender a secret from their clients, Haruhi works alongside six distinct personalities: the cool and calculating Kyoya Ootori, the mischievous Hitachiin twins Hikaru and Kaoru, the sweet and childlike Mitsukuni "Honey" Haninozuka, and his stoic, protective cousin Takashi "Mori" Morinozuka.

The 11-episode television series follows Haruhi as she navigates the absurd world of high society and the host club’s over-the-top antics. She learns the specific roles each host plays, from the "princely" type to the "little devil" twins, while slowly forming genuine friendships with them. A central narrative arc is Tamaki’s denial of his growing romantic feelings for Haruhi, whom he publicly insists is his "daughter" to maintain the club's family-like dynamic. Simultaneously, Haruhi’s practical nature and ability to see the twins as individuals causes Hikaru to develop his own complicated feelings for her, leading to tension within the group. The series also explores the personal struggles behind the boys’ wealthy facades, including family pressure, loneliness, and the desire for acceptance.

The live-action story continues directly from the television series’ conclusion in a feature film released in 2012. Having spent a year in the club, Haruhi becomes flustered after reading a magazine article that convinces her she has fallen in love with Tamaki. Meanwhile, the Host Club enters the annual Ouran Festival, competing against other clubs to win the right to use the school’s luxurious Central Salon. A new complication arises with the arrival of Princess Michelle Monaru of Singapore, a spoiled honorary student who appears to have romantic designs on Tamaki. As the competition unfolds, Haruhi discovers that Michelle is not a rival for Tamaki’s affection but a lonely girl trying to reconcile with her estranged brother, Lawrence. The hosts band together to win the festival and help reunite the siblings, leading to a final, accidental kiss between Haruhi and Tamaki that resolves the romantic tension built throughout the series.