While Ahn Jinjoo is busy tending to her own friends' problems—like Sorim's secret crush on their friend Donghyuck who is practically their brother, and an even weirder issue of Donghyuck dating Jinjoo's younger sister—her own prob

Park Jinyoung who has been suffering with his family's debt and daily expenses is now experiencing an amnesia due to a mild traumatic brain injury when he passed out in front of the car of Kim Haesung, the eldest child of the owner of a large engineering firm in South Korea. Thinking that she's partly responsible for it, Haesung tries to help recover his memories.

Yeseul knew Mark since she was 7 years old. He was just that boy that lives next door. But her perspective started to change when her last year in high school in GI Academy had a Mark Tuan in it.