Lee Sungyeol is an outgoing guy who's pretty popular. He's a ladies man who doesn't believe in love. Seo Haneul isn't your normal girl, not at all. She's not destined to fall in love.  Do Kyungsoo is your normal boy. He has been in love but got his heart broken. 

Yang Gaeun, a sophomore in high school, was new to SHS. She's as innocent as they come. She's never had a boyfriend much less talked to a boy as anything more than a friend. She's beautiful but guys don't find it fun to go for the Mary especially when they're going to get nowhere. Nam Woohyun