Papiyas

"When the white light and black shadow mix, the horn of the underworld awakens, and eternal darkness is born," is a legend passed down in the underworld about a legendary berserker known as the "Sixth Heaven Demon King." Not even Brunhilde, Zeus, Hermes, or Odin knew of its existence, and only a few related to the underworld like Beelzebub and Hades were aware, and even they only saw its form for the first time during Ragnarok.

It is a monster that is said to have nearly destroyed the underworld before Hades ruled it, but then it suddenly vanished and was never resurrected, leading Hades to believe it was merely a myth or nonexistent. Beelzebub collected the remnants of Papiyas that once existed in the underworld, secretly cultivated it, and created a seed that was implanted into Zerofuku. Its previous disappearance was due to its body not being able to withstand its own excessive power, but using Zerofuku as a host, it now possesses a body far more robust than before.

Hades himself admits that its strength is so great that it surpasses any ordinary god, and it can freely transform its body to generate weapons for battle.