Joohyun's life is Perfect but then she was formerly known as Irene the Happy Virus. Keyword: 'formerly'. Yes, she was formerly school's Happy Virus. 

A traggic accident happened in her life that made her hate, scold, and being cold to everyone. Everyone in the school are still confused about what really happened to her. She wouldn't talk to anyone. Neither her bestfriends nor teachers. She always skips classes and she lost her friends. She became a lonely, sad, traggic and horrible person.

But then, she met Kang Seulgi. The school's new Happy Virus. She just transferred to the school but she made so many friends for being a Happy Virus, Bubbly, Cute and Charismatic but at the same time Adorable.

She was so irritated at Seulgi for annoying her everyday. She talks to her and Irene always ignore her but she didn't stop talking to her.

But then one day, Irene start talking to her.

What did Seulgi do that Irene start talking to her?