They called themselves the "Valkyrie" coming through a portal hidden in the walls looking like fatal warriors and dragging me into their world saying I was their "Healer"  

A girl who's a vampire and a boy who's a human    One fell dead and one up alive    Girl and Boy 

Hwanwoong first finds a light between Areum when their eyes met in the classroom... Hwanwoong asked Areum for a favor and agreed!  Areum told Hwanwoong to meet her at the "Clamest Coffee Cafe" after school.