My Tutor Friend (2003)
My Tutor Friend (; lit. "Tutoring a Student of the Same Age") is a 2003 South Korean romantic comedy film starring Kim Ha-neul and Kwon Sang-woo. Unglamorous Su-wan is a sophomore in college who gets hired to tutor rich troublemaker Ji-hoon, who is repeating his senior year of high school for the third time.
More at Wikipedia.