Yukimi, a pleasantly plump student in junior high, discovers a mystical dumbbell that has the power to transform her into the alluring and slim young lady, Miyuki. Clad in a provocative outfit, Yukimi must face the challenge of confronting an immoral three-star chef who targets adolescent females with high-calorie delights and questionable weight loss products. All the while, Yukimi must keep her true identity hidden from her peers and family.