25 years old Oh SooA is normal contract worker with the nickname Ya-Su by her co-worker which means 'Monster' in Korean old folks story, only due to her plain look and not even trying to get better with make up. She broke up with her boyfriend via Gatalk on her anniversary and also on the day she decided to be the 21 years olds Oh SooA who was pretty and fashionable back then. In her fancy red dress, she decided to hang out in a Sundusfy Bar and meet a handsome stranger. The two of them talked to each other , drunk and end up in a very very dangerous relationship afterwards DISCLAIMER : PLEASE DONT PRETEND AS IF YOU'RE OH SOOA, YOU DONT WANNA BE LIKE HER

SHIM EUNHA Came from a very poor family, drunk father, gambler mother but she was gifted with a very high IQ. She was hated by the entire neighbourhood due to her parents , and she was hated in school , saying she was too smart which made her ignorant , but in fact , she was just a very introverted person. She has a very small circle of friend, which was only Kim Youngbin , the kid next door, her partner in crime and one of her only besties. LEE JAEYOON Partially blind since birth. He was not entirely blind, he could sometimes see lights , but most of his time, it was all black. Wealthy parents , yet was not accepted due to his imperfection. He can play the piano well, he likes talking but he has no friends and always at home , in his room. Due to some reasons, Jaeyoon's mother knew how was Eunha's performance in her studies, so trying to be a responsible parent, she hired Eunha to be Jaeyoon's home tutor after school, knowing how Eunha was living in. She was even offered with high class education , as long as she managed to teach Jaeyoon everything she learnt at school. The first met was awkward and horrible, but as time goes by , the two of them were getting close. But after a while, Jaeyoon's sight suddenly gets better and Eunha suddenly went missing....

Nami and Inseong were two childhood friends, growing up together and always being known as Childhood Lovers in their neighborhood. Inseong was a hyper, spoiled brat and wealthy 16 years old. Nami was a shy but savage, brilliant and living in a middle class family. Her father owned a cafe named Nami Station, taken from her name.