In the present day, Osamu Kirin sees the Grim Comet approaching. Meanwhile, in the feudal era, Towa’s life is in danger after she uses her Zanseiken. The Spirit of the Tree of Ages orders the half-demon princesses to go destroy the Grim Comet.

To destroy the Grim Comet, Towa, Moroha, and Setsuna must travel to the present day using the Windmill of Time, but Meidomaru stands in their way. Kirinmaru takes Rion and tries to travel across time by force.