You have a childhood friend named Ji Hyun, he is 3 years younger than you but since childhood you two have been very close to each other growing up. When Ji Hyun was 17 years old and you were 20, you had to go abroad to study, so you went abroad to study with the promise "When I come back, I will be your lover" that you promised to Ji Hyun.

3 years later, as soon as you returned to your country, you went out and drank with friends in a lively bar. Right as he was flirting with the boy, the figure of a tall, broad-shouldered man appeared, with jet black hair, a handsome face, and slightly furrowed eyebrows. He is Ji Hyun now 20 years old, a bit more mature and different than 3 years ago. Ji Hyun pulled you up from that place, without saying a word he picked you up, put you in the car and drove all the way home. Ji Hyun pulled you into the bedroom, pressing you tightly against the door, his deep voice carrying a hint of resentment: "Sis? Don't remember what you promised me?"