"Yoodam oppa never let me go out and play with the boys,"

Yoon Yoo-Jin (14) -- Yoojin, Born 24 February 2003, is the younger of the twins. she is so frail, that's why her brother is very protective to her. But Yoo-Jin always prefers playing with boys. Yoojin thinks Yoodam is very mean because he gets to hangout with all his best friends meanwhile he doesn't allow Yoojin to go out of the house all the time. 

"Yoojin has to stay at home, i don't want her to get hurt," 

Yoon Yoo-Dam (14) -- Yoodam is the elder of the twins. He loves his twin sister very much. He knows that his sister is very frail and he is totally conscious of it. He doesn't want his sister to get hurt. but sometimes, he went over-protective to his sister because he simply doesn't want his sister to be sick. Yoodam and Yoojin are practically inseparable.

"I gotta sneak into the house just to see her. like the song i sang, 'they say that age ain't nothing but a number' , I  Just need to see her once and for all,"

Arredondo Samuel/Kim Samuel (16) -- Samuel is a sophomore at Yoojin's school. they have met each other since the beginning of their Elemetary school years. Samuel have been watching all over her. Yoojin is his first love and it has been years he kept it for himself. but now, Samuel has this urge to confess his feelings towards her. meanwhile, Yoodam has this urge to not let anybody near to his sister.

"I am a box of present for you, i'm sure you know that.  I wanted you to know i am always here beside you,"

Lee Dae-Hwi (17) -- Dae-hwi is a senior student at Yoojin's school who is apparently in love with Yoojin. He always sends flowers and presents for her since the beginning of the term. and he always annotated his name as Yoojin's secret admirer.

"I might scare you with my voice, but i will treat you better than anyone else."

Kang Daniel (22) -- the between yoojin and Daniel is really far away. Daniel is a guy living next door. He moved next door with his family 8 years ago and both families has a really close relationship since then. Yoojin and Yoodam has always been tailing Daniel when they were little. Yoodam only trusts Daniel when it comes to Yoojin. nobody else could he entrust his younger twin sister in this world but Daniel. Daniel has a low and husky voice which sometime scares Yoojin. 

"I can show you how much i love you through the numbers of our days spent together.

Park Ji-Hoon (18) - Jihoon is a very smart and cute guy. He tutors mathematics and science for the freshmen who are lacking in those fields. Jihoon is very patient and kind that's why every other freshmen would line up to have tutoring class with him. But among those hundreds of girls lining up, He only tutors one, and it's Yoojin. nobody knows why Jihoon chooses to tutor Yoojin. it wasn't for the teacher's orders of course. but judging from what currently happened, Jihoon has been interested and attracted to the girl without him knowing.

"She has been doing contemporary dance since she was five. And I always see the shine in her when she dances," 

Hong Eun-Ki (20) - Eun-Ki was one of Yoo-Jin's friends at the dancing academy. Both of them are actually the phenomenal couple at the academy after their debut at the joint stage last summer. Eun-Ki bluntly said that he was interested in Yoo-Jin even though he was 6 years older than her. It was no any secret that Eun-Ki was joining the competition to win her heart and he would probably be the big three chaser, along with Jihoon and Samuel.

"If Only she wasn't my younger cousin, I would probably be chasing after her, just like Eun-Ki and the others,"

Yoon Hui-Seok (20) - Huiseok was one of Yoojin and yoodam's cousin. He was a student at Kyunghee Engineering college and he was one of the closest person to the twins. Huiseok always treats the twins like his own siblings and he always stood before Yoojin when she got teased. there was one popular saying among the Yoon family, "Whom ever is trying to get yoojin must past the corpse of Yoon Jisung and Yoon Huiseok.

"Yoodam has to work on the sister issue. if he really cares about Yoojin, he wouldn't have let Yoojin to stay alone like this,"

Choi Tae-Woong (23) - Taewoong met Yoojin through Jisung. He was one of Jisung's closest homey. Taewoong is very protective when it comes to Yoojin, he really cares about the girl. Anyone who sees their affection might have thought that he was attracted to the girl. But nobody knows about that yet. 

"Teasing Yoojin is one of my most favorite activity during free time,"

Kim Jae-Han (22)- Jaehan owns a flower shop near the school. it wasn't a new story if all the boys at school would come to his shop everytime Yoojin was admitted to the hospital. And it was his liberty to tease Yoojin whenever that event occured. To Jaehan, it was fun teasing the younger.

"I would just enjoy taking care of Yoojin. And i would have to enjoy being around this popular little girl,"

Joo Jin-Woo (25) - One of the eldest guy in the clique Daniel was in, together with Daniel, Taewoong, Jisung, and Jaehan. Five of them were close since Daniel and Jaehan moved to the neighborhood. Jinwoo wasn't as talkative as the other four, he would just stay in silence or reacting to every other comment with a smile. He doesn't talk much but he is always there to carry Yoojin on his back to the hospital.