Ranjou Himeko

Neither too thin nor too thick A plump young lady with a body shape and flesh that is easily liked by men.
She is a third year student at the school and serves as the student council president.
She is a mirror student who is polite and kind to others.
However, she becomes harsh towards people she dislikes and shows her dark side.
The moment she said the word "fat," she thought she had no life.
She has a habit of being more interested in sex than most people, and
she says that naughty things are bad and evil.

“If you keep thinking about naughty things, I’ll blow your mind!”

From https://gyutto.com/i/item115308?select_uaflag=1