Divine Blood: Magnets
At age 16 in the Bravura Academy, Jeon Yoon-Ji is renowned as the top scorer of the school. The vice president of the student council who is in charge of student discipline in many matters. And she is regarded as the bad-ass wielder of the backscratcher of imminent beatdown.
But she wasn't always 16.
This takes place in a range from 8 to 2 years before the novel.