A gate to another dimension has burst open, and from it emerge gigantic invincible creatures that threaten all of humanity. Earth's only defense is a mysterious group of warriors who have co-opted the alien technology in order to fight back!
E1
The gate to an unknown world opens in Mikado City, which faces malicious invaders called Neighbors. An agency called Border responds to the attack.
Border agents hurry to the site of a Neighbor attack, only to find it in ruins. Meanwhile, Osamu tries to size up Yuma, a self-proclaimed Neighbor.
Trion soldiers enter through a irregular gate that opens at Osamu's school. Wanting to protect his peers, he charges recklessly towards the Marmod.
Osamu reluctantly takes credit for defeating the Marmod to cover for Yuma, but is then chewed out for unauthorized use of a trigger in real combat.
Kitora gallantly takes on a Trion soldier dubbed the Ilgar, but is thwarted when it goes into self-destruct mode and heads toward the city.