Shun Ukiya, the focus of the series, is a young Japanese schoolboy (who permanently wears a bandage over his nose, the only exception being his appearance in the final chapter of Gatekeepers 21) with a deep passion for kendo. Ukiya discovers that he has the ability to open the Gate of Gales in a chance encounter with an Invader attack near his hometown, where he meets fellow Gate Keeper and childhood friend, Ruriko Ikusawa. He is subsequently invited to join A.E.G.I.S. after discovering the existence of Invaders and of A.E.G.I.S. His Gate color is blue.