Son Gokū

The is a demon sealed within Rōshi of Iwagakure. Little is known about the beast, only that it allowed Rōshi to use its Lava Release abilities, a combination of fire and earth the likes of which have not been seen outside kekkei genkai. Kisame Hoshigaki of Akatsuki had difficulty capturing Rōshi because of this. The Four-Tails was later extracted and sealed, leading to Rōshi's death.