Naga Sotuva was originally a dragon and he was known as the Underwater Sea Dragon. He resided in underground sea tunnels. One day, Sea Dragon found a portal. He entered the portal and emerged in an underground realm of chaos. Sea Dragon explored the realm but got lost in a maze. He was soon found by the evil warlord Ashtar. Ashtar used his dark magic to twist the dragon's body. Sea Dragon was reshaped into a genderless form consisting only of claws, a long body, and a head. Ashtar decided to rename Sea Dragon as Naga Sotuva. It was confided to a waterfall where an endless stream of water flowed from its mouth. Naga Sotuva was forced to guard Ashtar's inner sanctum for the rest of eternity.
A millennium later, the underground realm of chaos was explored by the ninja Ryu Hayabusa. Ryu was searching for his girlfriend, Irene Lew, who was abducted by Ashtar. During the search, Ryu encountered Naga Sotuva at the end of the maze. Naga was blocking Ryu's path to Ashtar's inner sanctum. They engaged in a battle. Naga used its claws to fight Ryu but it was no match for the ninja's superior speed and combat skills. Ryu won the battle and used his sword to kill Naga. By losing, Naga died and its torment finally ended.
After the battle was over, Ryu continued searching for Irene.
- The Naga Sotuva is referred to as both a dinosaur and a dragon in the instruction manual of the game, despite not resembling either.