It's the season that living things come out of hibernation. However, Ginko is confined to the mountain where winter still continues. He looks for "nushi", the guardian of this mountain, in order to learn the reason.
At the request of Tan'yuu, Ginko sets off to investigate a phenomenon that might be related to a dangerous mushi, much to the chagrin of Kumado Minai, the current head of a long line of mushishi, who's in charge of the area. As Ginko and Kumado get to the bottom of the Path of Thorns, the secret of the Minai line of mushishi is revealed.