One March, Oriko "Okko" Seki with her parents, Shoji and Sakiko, embark on a journey to the ritual dance of Hananoyu for the annual Shinto spring festival that celebrates the rejuvenating powers of the hot springs. Unfortunately, tragedy strikes when they get into a car accident that results in the loss of her parents. Consequently, Okko relocates to live with her grandmother, Mineko, at the Harunoya Inn, situated in the picturesque Hananoyu hot spa town nestled in the shadow of Mount Ikoma in Kongō-Ikoma-Kisen Quasi-National Park near Osaka.
At the Harunoya Inn, the awkward and timid girl quickly finds friendship with the ghost of Makoto "Uribo" Tachiuri, who happened to be her grandmother's childhood friend and former neighbor. Uribo encourages Okko to take up the role of junior innkeeper for her grandmother. Initially, she struggles with her new responsibilities and feels overwhelmed, especially wearing the formal kimono that comes with the job. However, thanks to Uribo's support, she gradually learns to manage her tasks with dedication.
While attending school, Okko encounters Matsuki Akino, known as Frilly Pink, a snooty girl who flaunts a pink Lolita fashion style. Matsuki’s family owns the upscale Shuko Ryokan, a direct competitor to Harunoya. The playful ghost, Uribo, stirs trouble for Matsuki by mischievously painting her face, leading to a retaliation from a ghostly girl named Miyo, who turns out to be Matsuki's deceased sister, mocking Okko’s innkeeping skills. As fate would have it, Okko’s ability to see and converse with Miyo draws her to stay at Harunoya Inn rather than her own family’s establishment.
In a turn of events, Okko invites a disheveled man and his son Akane to the inn, firmly believing that "no one should be turned away." The staff soon learns about the heartfelt loss Akane suffered, which has left him withdrawn. After a request for cake exposes the inn's lack of such treats, Okko, filled with inspiration, whips up a new recipe for a "hot bath" pudding that resembles the soothing hot spring water. The pudding receives high praise from Akane and his father, leading to a glowing review in a magazine, attracting more visitors to the inn.
As summer approaches, a fortune teller named Glory Suiryo takes Okko on a shopping spree. However, a sudden panic attack haunts Okko as memories of the fatal accident surface. With compassion, Glory shares her own story, providing comfort to Okko, who envisions her deceased parents alongside Uribo and Miyo for reassurance.
A mystical encounter occurs when Okko unwraps a bell from her late grandfather, accidentally freeing Suzuki, a baby demon. Although initially greeted with annoyance, Okko soon finds herself employing the ghosts and the demon to assist her with the inn’s operations. As Okko nurtures her happiness and begins to let go of her grief, Suzuki realizes that she is starting to lose her ability to perceive ghosts.
When Matsuki and Okko are selected to perform at the town’s ritual dance during the spring festival, the duo engages in a humorous rehearsal where Matsuki's grace clashes with Okko's clumsiness, resulting in an all-out argument which leaves their instructor dismayed.
As winter descends, a young boy named Shota Kise arrives at the inn with his parents, seeking the healing waters. Shota's father expresses his dissatisfaction with the food served, prompting Okko to remember Matsuki’s culinary skills. Choosing to set aside their rivalry, she seeks Matsuki’s advice, which leads to a remarkable improvement in the family’s dining experience. However, an unexpected revelation emerges: Shota's father was involved in a tragic car accident that took the lives of Okko's parents. Overwhelmed with heartbreak, Okko runs away, distraught, but finds solace in Glory's timely arrival, who comforts her. In a moment filled with compassion, Okko invites the Kises to stay, providing them refuge.
In a heartwarming culmination, after reconciling over months, both Okko and Matsuki perform beautifully at the annual ritual dance during the Shinto spring festival. As they embrace their shared experiences, the ghosts bid farewell, moving on to their next life, with the promise of reuniting someday.
