Min-hyeok and Sang-mi are a couple since high school. They have never had sex until they became adults. Min-hyeok is the only one who imagines while watching pornographic videos. Min-hyeok is ready, and made up his mind to ask Sang-mi to have her first sex. However, Sang-mi has no desire to have her first sex with Min-hyeok. She hopes it will be an unforgettable experience since they are in love. So Sang-mi suggests to him for them to practice sex first.