"Okashi na Tensei Episode 1 begins at the Patissier World Tournament, where the protagonist, a prominent patissier, collapses during the final round of the "Confectionery Sculpture" competition. He wakes up as a boy named Pastry Mille Morteln, commonly known as Pas, in the Morteln territory, a burgeoning settlement thriving under the leadership of his father, Casserole Mille Morteln.

Pas harbors a passion for sweets, an ambition hindered by the territory's sugar shortage. When the overseer Feuille announces a successful bean harvest, Pas is thrilled by the prospects. However, the joy is short-lived, as Feuille warns of an impending bandit invasion from the County of Retes. This news strengthens Pas's resolve to defend his homeland.

Faced with the looming conflict, Casserole decides to expedite Pas's Sanctification Ceremony, a coming-of-age ritual symbolizing adulthood. Though initially shocked, Pas's mother Agnes and older sister Josephine agree. Pas, though overwhelmed, prepares for the responsibilities adulthood entails.

Pas and Casserole travel to the capital city of Bovaldia for the ceremony. The city fascinates Pas with its abundance of food and sweets, especially the scarce ingredients brown sugar and fruits. At the market, they discuss Bonkas, a sour apple variety unavailable in their homeland, prompting Pas to express interest in cultivating them.

During the ceremony, Pas is isolated to measure and potentially amplify his magical powers. Despite the darkness and silence, Pas's thoughts drift to the culinary possibilities of Bonkas, and he dreams of a world filled with his desserts.

The episode ends with Pas and his father secretly eating the finest Bonkas they had purchased earlier. Pas reaffirms his desire for a world full of sweets and vows to begin his endeavor with an apple pie."