It is May, 1969 in Japan. As a new era of prosperity begins for this small country, the world at large has seen a rise in unnatural disasters. A secret organization, known as A.E.G.I.S. (Alien Exterminating Global Intercept System), has traced their roots to entities known as “Invaders”. In an effort to prevent further devastation, the Far Eastern branch is searching for individuals who possess the power to open “gates”; also known as “Gate Keepers”.
Meanwhile, we are introduced to a teenager named Ukiya Shun, who lives with his mother and younger sister Saemi. Ukiya’s world drastically changes when his home is endangered in a battle between a group of Invaders and the first Far Eastern Branch recruit, Ruriko Ikusawa. Ukiya’s anger over the jeopardy to his home causes him to unknowingly open a gate, which he uses to single-handedly defeat the Invader threat.
Les Envahisseurs cherchent à s'emparer de l'amplificateur d'AEGIS. Le commandant d'AEGIS décide de faire appel à son meilleur élément, le Gate Keeper Ruriko Ikusawa. Malheureusement, celle-ci se retrouve débordée par des adversaires. C'est alors que Shun Ukiya intervient malgré lui dans la bataille...
