JeongieBaby's Favorite

They want Yoon's heart for some (probably) old rich guy. That's why coach told to that other girldude to shoot Yoon in the head, so they can take the heart. That's why those people in suits were checking their heartbeats - they probably want a heart with low heartbeats. That's why they take kids from streets, they are just "hearts" being grown for someone else. That's why that principalteacher told to Lee Chae Eun that only the rich people are allowed to love (or whatever), because they can buy themselves a new heart when theirs nears it's end.