Proboscis fever was prevalent in the Edo period and is said to be an incurable disease.
A savior appears who cures the fever, and the mysterious masked savior calls himself Donguri Tengu. The mother of a young brother and sister is infected with proboscis fever, and the older brother Ginnosuke heads to Edo to meet Donguri Tengu in order to save his mother. On the way, Ginnosuke tries to save a heron from being attacked by a hawk, but ends up killing the hawk. However, that hawk is a hawk that the general cherishes...