Taimatsu/Tailed Beast

Kasai (火災, Kasai) is the name given to the entity residing in the Matatabi Cursed Seal as a result of Orochimaru's cultivation of a small sample of the Nibi's chakra, enhanced into a much larger amount. This chakra was later mixed into a potion for the Cursed Seal it had been created for, and gave it sentience as a byproduct. Infused into Taimatsu's test tube, he was placed into stasis, while evolving at the same time.

After Taimatsu's release, Kasai was awakened as well. Thrust into a new world alongside an equally inexperienced and ignorant partner, Kasai grew up independently of his genetic source, the original Two Tails. Becoming known as a hero and a sage, Kasai joins his partner Taimatsu in his important job, helping him bring in criminals to the Blood Prison and maintain stability between nations.