"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 adressed to him. Rather, it's addressed to an old accquaintance, Aya Tozawa, so he decides to visit her. Ginko is concerned about Aya, as she is still searching for her sister, who has been trapped in an Uroana for 5 years.
Les Uromatori créent des trous dans l'espace : c'est la base de la communication à distance des mushishi. Malheureusement, la sœur d'une petite fille s'est perdue dans l'un de ces trous.
"現世には数知れぬ洞が―“虚穴”が開いている。足を踏み入れし者は回帰を願いつつも記憶を失くし、心を喪くし、彷徨うばかり―。"
깅코는 고치에서 편지를 받지만 그 편지는 그에게 오는 것이 아니라 아야라고 불리는 누군가에 대한 것이기 때문에 이 오래된 지인을 만나러 간다. 깅코는 5년째 갇혀지내는 언리를 찾아 헤매고 있는 아야를 걱정한다.
兔泽家是负责养护虫师的通信工具“虚”的一族。因为一次意外，妹妹绮被封闭空间里夺路而逃的“虚”带往虚穴，生死不明。多年来，姐姐绪始终没有放弃寻找妹妹。为了让绪彻底死心，银古带她进入大虚穴，那是无限深广的迷宫，只有前人虫师留下的铁链可供辨识出路。被绝望吞噬的绪，要如何从彼岸世界带回孪生妹妹呢？
