Mushi-Shi

"There are countless fissures in the physical world. Those who vanish like smoke are lost in such hollows. Without their memories, without their souls..." Ginko receives a letter in a cocoon but it isn't to him but to someone he already knows, called Aya, so he later goes to meet this old acquaintance. Ginko is concerned about Aya as she is still searching for her sister, who has been trapped in an Uroana for 5 years.