Ash opens the door to Mallow's family restaurant, Aina's Kitchen, only to receive a face full of flour. Abe was preparing for the annual Alola Bread Festival when he injured his back whilst carrying sacks of flour. Mallow's older brother Ulu and his Lickitung appears at the restaurant entry, much to everyone's shock. Mallow enthusiastically greets her brother. Ulu meets Ash, Rotom Pokédex, Pikachu, Poipole and the now evolved Steenee for the first time. Ulu announces that he wishes to compete in the Alola Bread Festival, with the year's theme being bread that both Pokemon and people can eat. The festival also offers a prize, which is a luxury liner cruise around Alola. Mallow serves lunch to Ash and her father, and Steenee is seen carrying dirty dishes.
Suddenly, a girl in a pink maid outfit and her Alolan Raichu enter the kitchen to pick up a lunch order. Ash is startled, and quickly realizes it is Nina, whom he met in Racing to a Big Event!. Ulu is ecstatic to see Nina; he looks up at her whilst sitting down on one knee, making her slightly uncomfortable. Mallow returns from the kitchen with Nina's order, interrupting Ulu's gazing. Nina leaves shortly after, stating that she looks forward to seeing Ulu's bread-baking skills, much to his delight. Ulu goes on to fantasize marrying Nina. Meanwhile, Team Rocket notice a poster for the festival and decide to enter because of the luxury cruise prize for the winner.
Time passes and Mallow's other classmates arrive at Aina's Kitchen. Sophocles, Lana, and Kiawe are familiar with Ulu and Lickitung, and Lillie introduces herself. The group are keen to try some of Ulu's cooking. They all take one bite, with Kiawe, Ash, Pikachu, and Steenee finding the bread sour, though everyone else finds it sweet. Ulu was revealed to have used a Grepa Berry in his bread, leading to the inconsistency in sample taste. To solve the dilemma, Ulu gets Lickitung to sort the sour from the sweet Grepa Berries. He quickly washes them, handing Kiawe one. To Kiawe's delight, the Grepa Berry is sweet, though he is also frustrated that Ulu did not get Lickitung to sort the Berries out before making the bread samples.
Later, the Alola Bread Festival begins, and several bakery stalls are set up with various breads, including glazed varieties. Team Rocket's stall is a red food van selling honey glazed bagels, proving popular with the crowd. In the meantime, Ash and his friends arrive at Ulu's empty stall to find a worried Mallow and a despondent Ulu. Mallow explains that Ulu became lovestruck after Nina came to visit the stall, but in his dazed state, Ulu sent all of the sweet Grepa Berries flying into a nearby Snorlax's mouth. Losing the vital ingredient and pressure to impress Nina with his baking skills, Ulu is left crippled.
Mallow suddenly remembers that there is a large amount of the sour Grepa Berries left over at Aina's Kitchen. Mallow suggests a sour jam would work well with Ulu's bread, and this revelation inspires some hope in Ulu. Kiawe collects the Berries using his Charizard, and the rest of the crew helps Ulu. Most of them wash the Berries and knee the dough, while Turtonator's flame helps with the pan baking and Mallow takes care of the jam, adding Steenee's Sweet Scent to the mix. The hot jam is used as a glaze over Ulu's baked bread. Team Rocket's customers abandon them for Ulu's creation, which quickly sells out. Nina arrives at Ulu's stall, thanking him for the delicious bread before introducing her fiancé, a man who attended her store on a daily basis. The revelation leaves Ulu dumbfounded and everyone feeling sympathy for him. Before Ulu can get too deep in his grief, an announcement comes through, alerting all participants that the result of the festival is about to be revealed, with everyone except Ulu and Steenee heading towards the awards stage. Steenee offers Ulu some much needed encouragement, with the two smiling at each other.
The judge announces the results, with Ulu and his Alolan Jam Bread winning the Alola Bread Festival. Mallow goes onstage to receive the golden trophy, which resembles a baguette with a chef's hat, whilst the audience claps. In the midst of her speech thanking her friends and family, Mallow notices Ulu's absence in the crowd. She pauses for a moment, and Steenee appears with a handwritten note from Ulu, announcing that he will continue his training journey. Meanwhile, Ulu and his Lickitung have already packed their bags and cooking equipment and boarded a ship heading towards the sunset.