Shinra, a boy living in a forest with mysterious powers, calls for Ginko, The Mushishi, to help him with his problems. While Ginko is staying with Shinra, he tells him all about Mushi and his powers. Later on, while walking in Shinra's house at night, Ginko finds a Mushi... But this isn't an ordinary Mushi, it's Shinra's grandmother!

On a rainy day Ginko takes a rest from his travels and comes across a man named Kourou who seems to be obsessed with a rainbow. To pass the time Kourou reminisces in his past, with the events which led to him pursuing rainbows whenever they appear. Ginko explains to him that the rainbow which he is searching for is actually a Mushi known as "Koda" but there seems to be more to it.

Ginko arrives at a village where the men are in a heated discussion about the mountain. After learning of Ginko's identity they ask for his help to find another Mushi-shi called Mujika, who happens to be the master of the mountain. While on his trek through the mountain Ginko stumbles across a boy who's also looking for Mujika. Later they manage to find Mujika but this isn't the end of it.

"When all are sheltering within, there comes an imitation of spring. Linger in bliss for too long and your flesh will soon be frozen..."

Caught in a blizzard, Ginko is decides to look for shelter and finds a home where the owner, Suzu allows him to stay the night. The next day Ginko sees a boy, Miharu who seems to be fascinated by Mushi. Ginko learns that Miharu once disappeared into the mountains in the winter and then suddenly came back in spring, able to see Mushi. Miharu has been repeating this since and it may be caused by a "Harumagari" so in the end, Ginko decides to teach him more about Mushi.

It is spring, and Ginko is taking a boat through a river, when the boat's boy, Kaji, asks Ginko whether he could help his mother, who's forgetting things and can't sleep. At first glance it may appear to be progressive amnesia, however something isn't right.

Ginko arrives at a secluded place, to meet an old acquaintance, who seems to be in charge of a large volume of archival, confidential text. Ginko is allowed to read it, and discovers it is the work of Tan'yu, a writer. Tan'yu is the descendant of the Karibusa family, being born with a black mark on a part of their body.

"All that is in my world... is seem sound taste and touch. That is all. That is enough..."

Finally able to reach a city, Ginko comes across a "biwa hoshi" named Amane, singing songs about Mushi and she is immediately able tell that he is a Mushi-shi. So she forces him to stay a night at an inn when she later reveals that she once saw a "Ganpuku" a very rare Mushi that will make the host see better and better until they die.

Taku is a peculiar young boy who has always wondered who the people were that always passed by the mountains during the rainy seasons. One day he meets a boy named Isaza, while catching fish. It seems that not only Taku can see the Komiyaku in the mountains however Isaza seems to know a lot more about the mountain than him.

"The world is filled with life unknown to man..."