Extreme Lesson: Yeong-soo saved money for 10 years since he graduated high school and now he's getting ready to go to college, which he has been putting off. Ji-eun is his girlfriend who has been by his side for the last 5 years, but the sex with her is quite boring. It almost feels like a chore. However, he doesn't want to break up with her, as they have been together for a long time. The first mock test comes up, but Yeong-soo has lost his will to go to college and his sexual desires.