Plus-Sized Elf Tomoatsu Naoe leads an ordinary life working as a massage therapist, but this changes when he encounters a peculiar client named Erufuda. During her visit, Naoe discovers her secret: she is actually an elf! After leaving her world, Erufuda fell in love with junk food and now cannot return home because of her weight gain. Naoe decides to help the elf with dieting so that she can eventually go back to her world. Although Erufuda puts in the work and reaches her goal, it does not take long for Naoe to stumble upon her again—and she has regained the lost pounds. As Naoe continues to give her advice, the two begin encountering other people from another world, all with the same desire to lose weight.