Sisters Rin and Rina run into trouble while looking for water in a desolate, mysterious world surrounded by decay and red fog.

The sisters are saved by Wakaba, a boy who has no memories of the past, and Rin invites him to tag along with them.

Wakaba is curious about all of the new things they encounter as they look for water, and Rina explains everything in great detail.

Wakaba takes a tremendous interest in all of the different kinds of Kemurikusa as the group journey to Sky Bridge.

The party continue their unsuccessful search for water. Soon, they are forced to travel on foot, making their situation even worse.

While the sisters get some rest in a train car, Wakaba heads out on his own to find Kemurikusa but becomes lost.