In the 20th century, a war of epic proportions was fought between humanity and monstrous creatures. Though they emerged as victors, the world now lives in constant fear of their monstrous overlords who remain concealed from public view. Bokka, a curious young boy, wonders about the fate of the valiant Meros Warriors who once bravely defended their realm from the demonic threat. It is during his musings that he meets Kurofune who enlightens him on the power of these warriors and their formidable I-bar machines. These heroes were the only ones able to perceive and hear the Melody of Oblivion, a ghostly apparition of a girl, trapped and waiting to be set free to save humankind.
In a fierce battle between Kurofune and a ferocious demon, Bokka makes a life-changing discovery that surpasses his wildest dreams – he too can perceive the melody previously limited to the warriors alone. The young boy embarks on a wondrous adventure, encountering monsters, their minions, allies, and partners, discovering the full extent of his newfound abilities. His continuing battles against evil are fueled by the hope of restoring the lost Boukyaku no Senritsu and freeing their world from the tyranny of the monsters who have cast a shadow over their once-beautiful soundscape.
