Hana is a 12-year-old girl from the Paldea region who admires the mail carrier Dragonite, and aims to be an ace mail carrier herself. One day, she is given a letter with no address, and suddenly has to scramble to find the sender. While running around town with her partner Fuecoco, she finally succeeds in finding the sender, a boy named Rio. She learns that Rio wrote the letter to his father, who is working away from home in the Kanto region, in order to wish him a happy birthday. But, it turns out that it's already the day of his birthday...
