In the Japanese city of Mikado, gates to a parallel world opened. Who lives there? Right—people just like us; they were called the Neighbors. They also lack unity, wars and conflicts raged, and as a result alien combat machines resembling giant insects infiltrated Earth. There were casualties; the city was slated for evacuation, but relations with a certain faction of Neighbors improved when they shared technology—now the peace of Mikado is guarded by Border, an organization of super‑fighters whose main base can be seen from everywhere. Citizens gradually grew accustomed to the alarms, and Border guards became TV stars and local heroes. Four years later, a 15‑year‑old loner with glasses named Osamu Mikumo stepped in for a newcomer whom the self‑proclaimed "cool" guys dragged into the wasteland of the forbidden zone. They chased away the hooligans, but suddenly gates opened, monsters appeared, and Osamu had to shine by using a "trigger"—the alien"s wondrous weapon. To the boy"s surprise, his new acquaintance named Yuma Kuga did the same, and turned out to be two heads taller as a fighter because he himself is not a Border trainee but a real alien. And what now? Deny everything or repent and hand over the new friend? In any case, you"ll never get bored with such "neighbors"!