This video is from a new high school musical Mnet drama I'm watching called MONSTAR (a combination of Monster & Star). I know the name's weird but the story's actually really cute. The stakes aren't as high as life and death but rather just typical, realistic challenges faced by high school kids these days. Even if you do not enjoy the show, there's no reason to not like their cover of BoA's Atlantic Princess.
I think they did a great job! :)
For comparison, I thought you'd like to listen to the original singer herself :)