On a quest to find the elusive “sky fish,” Meliodas and Hawk reach a palace suspended in the sky. The inhabitants are diligently organizing a ceremony designed to shield their realm from a fearsome creature that emerges every 3,000 years. However, before they can finish the ritual, the Six Knights of Black, an army from the Demon Clan, break the seal on the beast, endangering all who reside in the Sky Palace.