This is a world where fairies, goddesses, and demons exist. The great country of Lioness is on the verge of extinction due to the secret activities of the demons. It was saved by the legendary knights of the Seven Deadly Sins, who are great sinners, and a princess. After that, the Lioness Kingdom regained peace, and some time has passed since then. The Seven Deadly Sins came to the borderland to celebrate the king's birthday in search of the legendary ingredient, the sky fish. The leader Meliodas and the pig Hawk who can speak human language flew to the sky world "Sky Palace" that exists above the clouds on the way to find the sky fish. The winged "Sky Wings" live in the Sky Palace. Meliodas was mistaken for a Sky Wing boy who broke the rules and was imprisoned. The Sky Palace prepared a ceremony to prevent the release of the fierce demon beast that has been sealed for three thousand years. However, the powerful demon group "Black Six Knights" led by "Belion" appeared in an attempt to break the seal and take the lives of the Sky Wings. In order to protect everyone from their cruel and ruthless hands, Meliodas and others fiercely confront the "Six Black Knights"!