Main Characters:

Han Ji Min (You)

An introvert who keeps a diary.

Bae Suzy

Your best friend

Jung Daehyun

Your crush. 

Yoo Youngjae

Daehyun's best friend

Son Na Eun

Rival

Minor Characters:

Han Ji Yong

Your brother

Bang Min Ah

Bang Yong Guk

Preview:

Dear diary,

It's the the first day of my new high school. I'm kind of nervous. Thank goodness Suzy entered the same school as me or I wouldn't know what to do at all. There are so many unfamiliar faces. I'm scared of the crowd. I feel so small. Where is Suzy? I'm really nervous.  I'm sitting alone at the cafeteria. There is still half an hour to my first lesson. I don't even have a clue where the lecture rooms are. What am I going to do? I'm not used to this. I guess there's a price for not interacting with anyone. How am I going to get through this first day if high school?