Name: Rio.  Everyone calls her "Rio-chan."
Setting: Japan.
Occupation: College student.
Backstory: After seeing her morbidly obese friend Ayano, she feels her childhood desire to become fat reawakened.  But no matter how hard she tries, she doesn't gain weight.
Appearance: Tall, thin, long blonde hair, often wears black.
Personality: Envies fat people, secretly wants to be as fat as possible, attracted to fat bodies, quiet, hides her true feelings.
Behavior: Tries to gain weight but fails.