Watanuki, a lonely high school student who can see "Ayakashi", creatures that is obsessed with the darkness on the human heart. One day when Watanuki wants to erase his abilities and lead a normal life, he is led by a butterfly and arrives at a mysterious "Shop". "I will grant any wish, but I will get the price for it." Yuko, the mysterious and beautiful mistress of the Shop, whispers to offer his "most important thing" in order to fulfill his wishes. Watanuki starts to live with Yuko and help the Shop. Eventually he gets along with his classmates Doumeki and Himawari, and as he meets people with his worries, he gets caught up in a big incident beyond his imagination.