While shopping for some flowers in her local market, Tamako Kitashirakawa, the daughter of a mochi shop owner, encounters a peculiar talking bird named Dera Mochimazzwi.
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, Dera has a run in with Shiori. After Dera ends up getting lost, Shiori escorts him back to Tamako's house, where Tamako attempts to become friends with her.
Anko becomes disappointed that she cannot go a museum with her friends, including a boy from her class she likes, because the market is preparing for a festival. Meanwhile, Dera is cast as an ornament for the festival's shrine.
Choi Mochimazzi, a fortune teller from Dera's homeland, 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.
As the Tamaya shop decides to put on a mochi pounding event for October 10, Mochi Day. Meanwhile, Tamako comes across her father playing a familiar song from her childhood.
With the school cultural festival approaching, the Baton Club manage to get a key time slot for the main stage. As Choi comes to the school to give the club her support, she notices a particular mark on Tamako's neck.
Word spreads about Tamako allegedly being a princess. Whilst Tamako herself feels she's not really a princess, the neighborhood have a meeting concerning Tamako, feeling she should probably go to Dera's homeland to be a princess, although Tamako herself feels otherwise.
