Now Kurama is over very old (300 yrs old in the anime and over 100 yrs old in the manga) 15 years ago, the spirit fox Yoko Kurama was thought to have been killed in a botched burglry. In actuallity, he was greatly injured. With the last bit of energy he had, Yoko turned into a spirit and saught refuge in the human world. There he became the proud baby of a human family named Suichi.(and that's not how you spell it). He would stay there for 10 years so his spirit energy could safetly recover. 15 years past, and Kurama is still there. He can't leave his human mother behind. But now, he has "priorities" toprotect....like his mother.

Now, jump to the dark tournoments. Kurama, Hiei and Kuwabara are fighting Team Ura Urishima in the semi finals. Kurama steps into the ring and is tricked by Ura Urishima. He begs Kurama to kill him because of what he's done. (and he'smaking a force field as this is going on and Kurama has no idea) Then once the force field is made, then he releases the Idunn box, which would turn the person except for the user into a hepless child once they breathed in the smoke. However, Kurama breaths too much and is turned back into Yoko. Now Kurama wanted to know the secret of this box to turn into Yoko once again.

Flash to after Team Urameshi beats Team Ura Urishima. Sazuka meets up with Kurama and Kuwabara and tells him how Toguro humiliated him in the past, so he wanted to show him that you could win without using just strength. So Sazuka made those items in orderto beat Toguro, however, he is defeated by Genkai. So he shows Kurama what he did to make the Idunn box and gives Kurama a juice that made the steam. And he gives another thing to Kuwabara Kurama says they're basically guinea pigs since Sazuka does not know of any affects. This is how Kurama will transform in the battle.