Chua, for you <3. 

Shinye    Popular and attractive girl studying in Seoul University, majoring in Science and Technology, Year 2. She is mildly rebellious, highly sought-after by men and is intelligent. Her best friend is Hyunseung. Loves to wear red lipstick but reason behind it is not revealed. She has rejected all of her suitors and claims that she does not want to be in a relationship. She has two images at home and out of her home, and only her best friend is aware of this. Only feels comfortable enough to reveal her true self around Hyunseung. She is good at analysing people's feelings, so much that she knows how her friends are feeling when she looks into their eyes. Hyunseung and Amber call her 'Stephanie' instead of her Korean name. 

Hyunseung   Popular boy studying in Seoul University, majoring in Science and Technology and is also in Year 2 as well. Is lanky, has orange hair and a gentle personality which attracts many female figures in school. Rumour has it that even female teachers are attracted to his gentle disposition as well. He is known to many in school as the perfect 'Prince Charming'. He is also highly intelligent, and Is Shinye's best friend. He is somehow in love with her but he himself is unaware of it, as he thinks it's normal to feel that way towards a female best friend. Does not display his emotions openly for a few reasons (not revealed either) and is kind towards everyone around him. Shinye is the only person who is able to sense his emotions and his lies simply do not work around her. Shinye calls him 'Seung' instead of his full name. 

Onew aka Jinki    New student who transfers into Seoul University in the later part of the series. Majors in Art, Year 3. Is talented in the arts and sports. His passion for basketball has allowed him to rise to become the President of the Basketball team in his school. He is tall and built, with brown hair and sharp features. He becomes popular quickly after transferring into Seoul University and is also highly sought-after by women. He is known to his friends by the name, 'Onew'. Girls in school are so crazy over him that they have set up a fanclub dedicated to him, known as 'Prince Onew FC'. Only those who are close to him know his real name. Although he appears to be lazy, he is in fact, intelligent as well. He was once a bully, and had bullied Shinye in her earlier years as a child, which was actually meant as a joke. After the incident when he saw Shinye cry, he vowed to never hurt another girl in his life. He has been looking for Shinye for the past 12 years of his life and wishes to apologise to her sincerely. 

Amber   A tomboy-ish girl studying in Seoul University, Year 2, majoring in Foreign Studies. She dresses up in boyish clothing and enjoys styling her blonde hair. She was born in California and can speak fluent English and Korean. Hyunseung tries to convince her to switch back to being a female and tells her that she has a 'pretty face' and that she 'shouldn't waste her youth away'. Surprised by Hyunseung's actions, she falls for him and blushes everytime she sees him, and tries to deny the fact that she is in love with him. She is good friends with Shinye but this only happens in the later part of the series. Amber is very wealthy as her father is one of the most recognised businessman in Korea. Her mother died when she was young and her relationship with her father is strained. She is the only child and her father pampers her, even though she hopes to be solely dependent on herself someday. 

For other characters.... Let me think it through ^_^