A nimble fat person is attractive.

I never thought reincarnation was actually real. Until that day... When I opened my eyes, I was in an unfamiliar world. Like many reincarnation stories, I was born as the handsome son of a beautiful mother and a fine-looking father—or so the story should have gone. This is a backwards tale where the protagonist, unaware of such values in a world where beauty and ugliness are reversed, struggles against the odds!