Ginko is waiting along the sea shore, for a transport to get him across the bay when he meets a man called Shirou, who lost his wife under strange circumstances. Ginko seems interested and decides to listen to his story about how he lost his wife in a swarm of sea snakes, during fog. Ginko later comes back with information on the Mushi that caused the bizarre events.

A lady named Aki discovered a green stain on her wedding gown, one year later she gave birth to a boy who, now grown up, has the same marks on his body. It turns out that the boy was originally born not as a human but as some shapeless green blob, which then turned into a human. Her husband asks for Ginko's help yet he is unable to save her son because it's the work of a "Watahaki".

"Build a fire - night comes... Light a fire - darkness comes... Hide the fire - flames arisen from corpses creep in..."

Ginko meets another Mushi-shi, which happens to be a young lady called Yahagi and surrounding the village she lives in is a new variety of Mushi growing on the mountain's fields. It's becoming so bad that the village people are at risk and as a last resort they plan to burn the entire mountain but Ginko doesn't think that this is the right option.