Large mysterious alien ships have been looming above Japanese towns for three years, filling the sky Everything changed three years ago. And yet, nothing has changed.

No weapon used against the invaders' ships had any success, beyond destroying part of japan and leaving its economy in shambles. JSDF is fighting a guerrilla battle against the aliens all over Japan.
America is joining the 'war' effort with more aggressive tactics, dividing Japan over the pacifist principle laid out in Art9. of their constitution.

But this may just be the mundane story of young middle schoolers.

"No matter what happens, I won't back down. At least not until this world filled with lies and deceit crumbles away. (...) The real threat to humankind is not invaders, but me."