The town where Yui lives was once surrounded by a dense forest. The forest has a legend of people being spirited away by the Tengu inhabited there. Yui remembers that 11 years ago Kayo disappeared in that forest. "Back then, I was right next to Kayo. But, why wasn't I chosen...?" Consumed in her thoughts, Yui steps into the last of the forest as if the swaying wind from the trees is calling her in...