School cleaner Nozomi Haruta was happy. She was supposed to marry her partner, her beloved, her soulmate, the handsome teacher Chitose Yokomizo, but when he secretly marries someone else, he ruins her dreams and breaks her heart. Also, maybe her mind? Seized by desperation, Nozomi photobombs his big wedding photograph by replacing the bride, steals the camera, and makes a run for it! Headlong into the path of a courier carrying Castella cakes! When she wakes up, she sees Chitose hovering over her, only it’s not him, but a being who calls himself Castella (as in the cake). For the next two weeks (the expiration date for the cakes), he will be Nozomi’s cake-based companion and help her get over her despair.