Rio Ueda is a third year (senior) who used to live in Tokyo.
Rio has a "Madonna presence" at school.
She is often seen wearing mascara and lipgloss.
After confessing to Kakeru Naruse, an underclassman who was a year younger than her, she became his girlfriend and talked to Kakeru more frequently, often hugging his arm and inviting him to cafes.
She is suspicious of Naho Takamiya.