Son Gokū

The is an unknown type of demon, who can manipulate lava, was sealed within an elderly man named Roushi, of unknown origin.

Background
It is currently unknown of what type of animal is the Four-Tails.

The Four-Tails Jinchūriki Roushi went on a journey to control the excessive power of the 4 tails that he has housed since childhood. At the end of his journey, by borrowing the 4 tails power he learned lava ninjutsu by fusing Fire and Earth natures. That torrent of lava could melt away anything.

Roushi was eventually defeated and captured by Kisame Hoshigaki right after his introduction. According to Kisame, he had a difficult battle because he had to face the unique elemental fusion of Fire and Earth.

The Four-Tails was later extracted and sealed, leading to the old man's death.

Abilities
Little is known about the Four-Tails' abilities. The Four-Tails Jinchūriki has made use of its Lava Ninjutsu attacks, which a is rarely seen special ability. It is unknown if this advanced nature is unique to the Four-Tails and its Jinchūriki or a kekkei genkai present in others.