[Theory] Juubi origin idea

[Hori]

I think Juubi is a summoning animal that once belonged to Rikudou sennin

 

[SagemodejubihostSasuke]

I think the Jubi is a god, that that. The sage could not even control him when he seal the jubi in him which shorten his life spam and made him have to split the jubi to 9 tailed beast. Jubi is pure evil energy manifested.

 

[H a n]

May have been something long before and was corrupted into the thing it is now.