Dead Dead Demon's Dededede Destruction

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 Article 9 of the Japanese constitution. But this may just be the mundane story of young high schoolers.