In the town of Staccato, demons suddenly descend and wreak havoc, threatening the entire country. The problem stems from a once‑strong barrier that has kept these demons from entering the human world. That barrier is now weakening because its guardian, Queen Horn of Sforzando, is losing strength after years of maintaining it. Hell King Bass attempts to break through the barrier and release their supreme leader, Kestra (Orchestra), a being of unparalleled power who is trapped somewhere in the human world.