Namju ga Eopseumyeon Nae Seongjeok i Manghanda

High school student Han Jiseo is perfectly happy to be reborn as an extra character in a manhwa. Her side character always scores second place in the entire school, after all! The male lead, Ju Yiwon, is welcome to first place; Jiseo's happy so long as she can get into university. But one day, Ju Yiwon doesn't come to school... and Jiseo scores zero on a test. "Don't tell me... my grades depend on the male lead?!" If Jiseo wants to make it to university, Ju Yiwon needs to be present. Thus begins Jiseo's ultimate mission: make sure the male lead attends school! (Summary adapted by me from Kakaopage.)