Tells about a little boy who fears the world around him and finds safety only when he is completely hidden under the covers of his futon. To him, a futon is a kekkai (spirit barrier) which can protect him from evil. When he is hospitalized, the boy discovers a beautiful girl unconscious in another room with her left hand sticking out of her blanket. When the girl's left hand is mysteriously cut off the next time the boy goes to see her, he regrets that he did not push her hand under her blanket when he could have, believing that some evil spirit had cut off her hand

from wikipedia