Shibuya Haruko is a high school student living in Tokyo. One night, she is instantly smitten by Kanagawa Kenichi, who is lying prone on a bridge. But Kenichi becomes far more interested in a girl he impulsively hits on, Mayumi, over the high-spirited Haruko.
Shiori accidentally angers the Smiling Man, a demon that has been latched onto her soul since birth, who in turn torments her into discovering the mystery behind the origin of the curse.