Ginko is on another adventure as he is brought to a very peculiar island, by a young boy Nagi. Ginko is taken to see a girl, who the island inhabitants refer to as "Ikigami" and is said to be able to perform miracles however Ginko discovers that there is more to this.

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.

While on his journey, Ginko stumbles upon a town which has yielded a great crop this year, thanks to their ancestors. However, it is said that someone must be sacrificed in exchange. Ginko finds this peculiar and decides to investigate further, by going to see the village "Saishu-sama" (chief mourner) who may have something to do with it.

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.