If you feel disappointed, troubled, helpless. Try asking what you wish from the girl with the black shadow and your wish will come true. Many people tried it before you and all of them succeeded but you must have something to exchange with your wish, something valuable enough, something equal to your wish.
Meet Mia, the girl who get involved into the chaos caused by the wish from many people to shadow girl unwillingly.
Meet the dark story that Mia unable to encounter.
Meet the cruelest exchange from the shadow girl that make you frighten.
Meet each character's concealing habit.
Everything can be found in one place, here.