Following the events of the television series, Haruhi Fujioka continues her journey at the renowned Ouran Academy. Coming from a humble background, Haruhi is determined to pay off her debt to the prestigious Host Club, which consists of six charming boys: the princely Tamaki Suoh, the cool and collected Kyoya Ootori, the mischievous twins Hikaru and Kaoru Hitachiin, the adorable Mitsukuni "Honey" Haninozuka, and the stoic Takashi "Mori" Morinozuka. These young men provide entertainment through their charming tea services and lighthearted banter. Haruhi’s involvement in the club is sparked by the accidental destruction of a valuable Renaissance vase.
Having dressed as a boy and adapted to the host culture for nearly a year, Haruhi feels at ease. However, her world turns upside down when she reads a romance magazine gifted by the eccentric occultist Umehito Nekozawa, which suggests she has feelings for Tamaki. This revelation complicates matters, especially for Hikaru, who secretly harbors feelings for Haruhi.
As the Host Club prepares for the annual Ouran Festival—a competition where the victor gains access to the luxurious Central Salon—they find themselves up against fierce contenders, including the Black Magic Club led by Nekozawa and the American Football Club, spearheaded by Takeshi Kuze, Kyoya's rival. The festival coincides with the visit of Princess Michelle Monaru from Singapore, an honorary student who craves attention and inadvertently threatens to create tension by showing interest in Tamaki, causing jealousy in Haruhi. Yet, it comes to light that Michelle's intentions are not what they seem; she is merely trying to reconcile her relationship with her estranged brother, Lawrence, following a family tragedy.
Complications arise when a valued book of Michelle's falls into the rain, prompting Haruhi to risk her safety to retrieve it, resulting in Tamaki getting injured while protecting her. Upon recognizing the Monaru family's true motivations, Tamaki's grandmother, Shizue Suoh, refuses to engage with them any further.
Seeing Michelle's loneliness, Haruhi resolves to help her find happiness by winning the festival. They invite Lawrence to Japan, presenting him to Michelle as her treasured family heirloom, a strategy that brings the siblings together. As it turns out, the lost book was a cookbook containing cherished family recipes, symbolizing Michelle's longing for shared moments with her brother, reinforcing their bond.
In an exciting turn of events, the Host Club wins the festival, earning the coveted Central Salon. During a heartfelt moment, Hikaru admits his affection for Haruhi but expresses contentment in her happiness with Tamaki. Later, while strolling by a river, Haruhi attempts to communicate her feelings but, in a comedic twist, trips and ends up kissing Tamaki, leaving them both embarrassed.
Throughout the closing credits, a delightful scene shows Haruhi finally savoring otoro, a luxury she had been deprived of long ago, symbolizing personal growth and newfound joy.
