"Ouran High School Host Club" centers around Haruhi Fujioka, a scholarship student at the prestigious Ouran Academy, an elite institution catering to the wealthy. While searching for a quiet place to study, Haruhi stumbles upon the Third Music Room, which is occupied by the Host Club—a group of six male students who entertain female clients with their charm and companionship. Accidentally breaking an expensive vase, Haruhi is forced to join the club to repay the debt. Due to Haruhi's androgynous appearance and practical nature, the club initially mistakes her for a boy and recruits her as a host. When the truth is revealed, Haruhi continues to participate, disguising as a male host to avoid complications.

The Host Club is led by Tamaki Suoh, a charismatic and flamboyant half-Japanese, half-French student who serves as the "king" of the group. The twins Kaoru and Hikaru Hitachiin specialize in playing up their brotherly bond to entertain clients, while Mitsukuni "Honey" Haninozuka, a small, childlike figure with a sweet demeanor, contrasts with his imposing cousin Takashi "Mori" Morinozuka, who acts as his protector. Kyoya Ootori, the vice-president, is the pragmatic and calculating strategist behind the club's operations. Together, they create an extravagant and whimsical environment for their clients, often engaging in themed events and playful antics.

As Haruhi becomes more involved with the Host Club, her down-to-earth personality and indifference to wealth challenge the privileged perspectives of the members, particularly Tamaki, who develops romantic feelings for her. The series explores themes of class disparity, identity, and relationships, blending comedy with moments of emotional depth. Haruhi's interactions with the club members lead to personal growth for both her and the hosts, as they navigate their own insecurities and familial expectations. The narrative also delves into the backgrounds of the characters, revealing their vulnerabilities and the pressures they face as heirs to influential families.

Throughout the series, the Host Club's dynamic evolves as friendships deepen and romantic tensions arise. Haruhi's presence disrupts the status quo, prompting the members to confront their own assumptions about love, friendship, and societal norms. The story balances humor, romance, and introspection, creating a narrative that appeals to a wide audience while maintaining a lighthearted tone. The series concludes with a focus on the bonds formed within the club and the impact Haruhi has had on their lives, leaving room for personal growth and future possibilities.