Whilst shopping for some flowers in her local market, Tamako Kitashirakawa, the daughter of a mochi shop owner, encounters a peculiar talking bird named Dela Mochimazzi that decides to follow her home. As Tamako and her younger sister Anko go to the public baths later that evening, Dela has Tamako's childhood friend, Mochizō Ōji, take him to the baths as well. As New Year's Eve arrives, with Dela having put on weight after gaining an affection for mochi, Dela almost chokes on a mochi, prompting the neighbourhood to help him out, overlooking Tamako's birthday.

As Valentine's Day approaches, Tamako suggests the shopping district should hold a Valentine campaign. However, Tamako's father, Mamedai, is against the campaign, believing it to be too modernised. As Tamako and Mochizō start shooting a commercial for the shopping district, Tamako's friend, Midori Tokiwa, feels conflicted by feelings she starts having around Tamako. At the screening of the commercial, Dela manages to stand in for the projector by projecting the image through his eyes. When the commercial finishes, Dela shows another video, this time a video message from his home country. As Valentine's Day arrives, Midori comes to terms a little with her feelings.

As a new school year starts, Tamako and her friend Kanna Makino ends up in the same class as badminton club member Shiori Asagiri. That morning, Dela has a run in with Shiori and falls in love with her. After Dela ends up getting lost, Shiori escorts her back to Tamako's house, where Tamako attempts to become friends with her. Due to coincidental situations with her family, Shiori soon ends up staying for dinner and joining Tamako to the baths. The next day, Shiori tries to work up the courage to thank Tamako for the other day, but has difficulties overcoming her shyness. As Shiori ends up helping her homeroom teacher to Tamako's house for a home visit, Tamako takes her to a coffee shop, where she is finally able to convey her feelings of gratitude. As the two become proper friends, Shiori gives her thanks to Dela for helping her out, though rejects his proposal of love. Afterwards, Tamako hears from Midori about how much courage it took for her to convey her feelings properly.

Choi Mochimazzi, a fortune teller from Dera's homeland, comes to stay at Tamako's house, revealing that both she and Dera come from the island's royal family. When Choi becomes annoyed by Dera gaining weight and forgetting his mission to find a bride for the island's prince, he claims he is being held against his will, leading her to be distrustful of the good will Tamako and the shopkeepers show towards her. As Choi tells fortunes as a mean's of paying back everyone's kindness, shopkeeper Sayuri Yumoto reveals she is getting married, much to the dismay of tofu shop owner Tomio Shimizu, who had a crush on her. This leads Choi to think about her own unrequited feelings for the prince, leading to her getting a fever after passing out in the bath. After Tamako helps her overcome some of her homesickness, she becomes a bit more accepting of everyone's kindness.

As the Tamaya shop decides to put on a mochi pounding event for October 10, Mochi Day, Anko asks Tamako to set some daifuku aside for Yuzuki, the boy she has a crush on, but can't bring herself to face him in person. Asked by Tamako to help, Mochizō learns that Anko is depressed because Yuzuki is transferring to another school on Mochi Day. As Mochi Day arrives, Tamako gives Anko the encouragement to see Yuzuki off before he leaves. Receiving some fresh mochi Tamako gave Anko, Yuzuki tells her that they'll see each other again when his family next comes to Tamaya for some mochi. Meanwhile, Tamako comes across Mamedai playing a familiar song from her childhood. The record store owner, Kunio Yaobi, tells Tamako and the others that the song was written by Mamedai for her late mother, Hinako.

As word spreads about Tamako allegedly being a princess, Tamako herself is more focused on collecting enough loyalty points to receive a medal from the shopping district. After Tamako earns her medal, Choi manages to fix Dera's communication features and get in contact with the prince, Mechya, who exchanges some words with Tamako before Dera breaks down again. Whilst Tamako herself feels she's not really a princess, the neighbourhood have a meeting concerning Tamako, feeling she should probably go, although Tamako herself feels otherwise. The next morning, Tamako panics when she can't find her medal, only to be given it by Mechya himself.

As the whole shopping district takes an interest in Mechya, Tamako feels a little confused by everything, the empty shopping district begins to remind her of when her mother died. When asked by Dera about what she thinks of the whole bride business, Tamako talks about how much the district has meant to her over the years. Tamako rushes to turn down Mechya's proposal, only to learn that she isn't actually a candidate, as Choi has misunderstood things. After the girls see them off, Choi and Mechya head back to their home country, only to realise they've left Dera behind. Come New Year's, Dera attempts to head back home by hiding himself in a bouquet, only to wind up in a box Mochizō has ordered for Tamako's birthday and end up right back on Tamako's doorstep.