A mayfly incubates in its egg for years and then hatches to live only for a day. In much the same way, you've spent your whole life hiding—hiding from your responsibilies, from studying, from socialising, hiding your feelings for a certain boy. Now that you've reached your final year of high school, you've decided that it's time to live your life and experience the trials and tribulations of being a teenager. It may seem hard at first but you've resolved to take it a day at a time, like a mayfly.

Kim Moonchul is famous in your school for being a flirt and a troublemaker. Although he doesn't have the typical looks of a playboy, girls fall for his charismatic smirk and clever wit. Somehow, he realises that he's never talked to you before or seen you with any guys and decides to see if he can charm you. Moonchul enjoys music, the only subject he makes an effort in, and has a painful past.

James Lee has been your friend since middle school and it didn't take very long for you to grow a crush on him. Naturally, you kept quiet about it, afraid of rejection and jeopardising your friendship, and so grew complacent with keeping your feelings a secret. James is tall, athletic and always has a smile on his face.

Kim Sooyoon is a boy in the grade below you. He enjoys fashion and music and somehow always seems to be where ever you are.

Jenn Im is your closest friend and yet you haven't told her about your feelings for James. Her bright, spunky and easygoing personality makes up for her short stature and she loves to vlog about her life, resulting in you featuring in most of her videos.