Charismatic, fierce, powerful, that's how Kai's fans describe him on stage. He appears to be a dance machine with an immense stage presence. He appears all giddy and joyful on variety shows and smiles happily at fans, that's what he's supposed to do being that he's an idol. But behind the image he has to put up, things are different. There's a lot going on behind closed doors and he's quite broken inside. It's ironic really; he's in a group that sings love songs yet he doesn't believe in love at all. 

When things get tough, by chance he meets Hana at the hospital. She's a doctor who suffers from depression, one who could fix sick people but not herself. Unexpectedly, their lives get tangled with each other; he can't stop thinking about her and she can't stop eyeing him every time they meet. Piece by piece, Hana puts his shattered heart back together while Kai shows her what it's like to smile again. 

"...this is going to sound weird, but I think I see the other half of my soul...and it's in you."