Story
The King of Hell had held Odin, the ruler of Norse gods, captive in the Land of the Dead with the help of Loki, the Trickster.
The Valkyries failed to save him, and ended up becoming sex slaves to the demons.

As a trade to free himself, Odin had the river source to the World Tree sealed, which will destroy the whole world.
But before that, Loki had Freya, Chief of Valkyries, captured to counter Odin's plot.

In order to prevent the World Tree from falling, Loki has to find two keys which are protected by two invincible Valkyries maids: Sigurd and Suvia.
And so Loki turned his lustful attention on Suvia, who was a Princess of Prishintia, leaving the chief Valkyrie Sigurd to his minion lieutenants...