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"  

That cookie was Ahn Hyejin's.

  "We call it... brain dead."   Yongsun felt her whole body collapse, letting her tears fall down. She couldn't blink, or breathe properly, the surroundings blurring as she drowned in her own tears. She felt the whole world crumble, as if there's no more tomorrow and she's dead now or something. And she wanted to die, so, so much, because what's the point of living now that Byul is half dead and the reason is her?  

There was nothing left in life for Moonbyul. Her life was meaningless. She had lost the love of her life, and from there, everything had been torn to pieces. But when her instincts make her save the woman on the street, could her life return?