Pulled by the sprightly, pink-robed Botan, Yusuke enters a realm that is not quite normal -- the Spirit World. There, Yusuke meets Koenma, a 700 year-old ruler with the body of a toddler, pacifier and all! But there's no rom for laughs as Koenma gives Yusuke an ordeal to restore his life. Hatching a Spirit Beast!

The oafish demon Gouki is using the stolen Orb of Baast to capture children's souls. If Yusuke doesn't track down and defeat this monster quickly, those souls will become the monster's next meal. But Gouki isn't the only one Yusuke has to worry about when the second thief suddenly appears. His name is Kurama, and to great surprise, he asks Yusuke for a favor...

Kurama and Hiei, two demons Yusuke beat in his first case, join Yusuke and Kuwabara to battle the Saint Beasts. This awkward alliance must learn to trust each other quickly, as they struggle through the Gate of Betrayal. And waiting just beyond this trap is the first Beast —- a giant made of solid stone!

Sensui makes his appearance, and battles Yusuke, Kuwabara, and Kurama. Sensui's abilities enable him to battle all three on equal footing. During the battle, Sensui manages to kidnap Kuwabara.