Harumagai (春まがい, lit. False Spring) is a false spring effect caused by the Usobuki. When the mushi behind it become active, the animals and plants in the surrounding area awaken briefly from hibernation, only to be put asleep again and fed off of by the mushi.

Created by the Usobuki mushi, all plants within a small area are induced to begin flowering and setting out leaves in the middle of winter, as though spring had come. Animals or humans are naturally drawn to this false springtime with the promise of food not otherwise available in the winter. Once within the false spring, the mushi can feed on the animals or humans.

They awaken normally again when the real spring arrives during this time the Usobuki transforms from its butterfly form to a flower like form and releases a distinct scent causing its victims to awaken.