Kyuubi: The pot and gourd that he summoned a while ago and made the demonic statue eat were two of old man Rikudou’s treasured tools. They possess a strong sealing technique that can seal away anything. If you end up in them, you can't get out... Kinkaku was sealed in the pot... While Ginkaku was sealed in the gourd. Most likely they were revived by Edo Tensei in order to be used in this war, and eventually they were sealed into those two treasured tools.
Guy: The Rikudou Sage and the Kinkaku-Ginkaku brothers... Those are names you hear only in legends. ...However, how are they related to the Kyuubi's chakra?
Kyuubi: A long time ago, those two challenged me to a fight... And I ate them. But after that... they greedily devoured the meat in my stomach... And absorbed my chakra!