It's 1969, and Japan is in the middle of a large economic boom. That doesn't mean that all is well, however. Mysterious
beings, called "invaders", are infiltrating Japan at an alarming rate. Earth Defense Organization AEGIS has a secret
weapon to battle the invaders - Ikusawa Izuniko, a schoolgirl who can open a dimension to another world and draw
devastating supernatural powers from it. One day on a routine assignment, AEGIS sensors detect an immense Gate
Power source in the area - one Ukia Shun, an estranged boy who was completely unaware of his amazing power.
Gatekeepers 21 ~
Gatekeepers 21 is set in 21st century, 32 years from the original Gatekeepers. In these 32 years, Earth
finally was set free from the invaders. Japan is prospered like never before. A.E.G.I.S still exists in smaller
scale to investigate more on the invaders and the mechanics of the gate. However, A.E.G.I.S network and
Earth Defense Agency has detected enormous amount of Invaders infiltration in the human society. Under
such circumstances, an elite Invader Hunters group is assembled with Ayane Isuzu and Miu Manduru as
their first two members.