In "Digital Beasts Adventure", the Metal Sea Dragon Beast is known as the Four Heavenly Kings of Darkness along with the Clown Emperor, the Mechanical Evil Dragon Beast, and the Puppet Beast, and he is the one who gets the powerful darkness from the Apocalypse Beast, and he resides in the Dark Tornado Mountain, and he is in charge of the sea, and he is the leader of the "Dark Army of the Deep Sea". After the chosen children defeated the Ultimate Vampire Beast and returned to the Digital World, the Infinite Dragon Beast and the other three Dark Kings attacked them, and thanks to the Goblin Beast saving their lives, the Metal Sea Dragon Beast used the Ultimate Wave Cannon to break the Goblin Beast's boundaries and kill it.
After escaping, the Chosen Child first faced the Steel Sea Dragon Beast. After defeating the Shell Beast, the Chosen Child accidentally fell into the Iron Dragon Beast's trap, and was locked into a hut by the Yaruga Beast and knocked unconscious. Only Mai and Asuka were slow enough to escape. They evolve into the Zouton Beast and the Flower Fairy Beast, defeating the Alucard Beast and rescuing the crowd. As they escape, however, they are overtaken by the Steel Sea Dragon Beast. When there was no way out, the Giant Whale Beast appeared and saved them.
The Iron Dragon summoned his right-hand man, the Frog Beast, and searched the ocean floor, eventually finding the Giant Whale, who had adjusted its air pressure. After a lot of hard work, the Giant Whale Beast finally got away from the Steel Sea Dragon Beast and came out of the sea, but at the same time the Steel Sea Dragon Beast also appeared. Everyone spreads out to deal with the Odd Frog Beast while dealing with the Steel Sea Dragon Beast. The Battle Tyrannosaurus was bitten by the Steel Dragon Beast and could not hold on much longer, but the Giant Whale Beast saved him. However, the Steel Sea Dragon Beast killed the Giant Whale Beast. The Battle Tyrannosaurus' furious blow drilled the Steel Dragon Beast in half. Both the Giant Whale Beast and the Steel Sea Dragon Beast died, and with the death of the Steel Sea Dragon Beast, the ocean of Dark Tornado Mountain disappeared. Ultimate Wave Cannon (Ultimate stream): a skill that fires an energy cannon attack from the front of its nose.
Hell Squeeze (Hell Squeeze): a skill that bends the body, releases light, and sends the target flying with bullets from a column of water.
Poseidon Divide (Poseidon Divide): a skill that manipulates the ocean, causing a huge tsunami that engulfs the opponent.
Flame Jet: Spews fiery flames from its mouth to burn enemies. Evolved from: Alucard Beast, Brachiosaurus Beast, Dagao Beast, Chibi Beast, Sea Devil Beast, Million Sea Dragon Beast, Mephistopheles Beast, Mecha Dragon Beast, Sha Wujing Beast, Wicked Sea Dragon Beast, and Giant Whale Beast in their full form;
Evolved into: Apocalypse Beast (with or without the other Dark Tetrarchs co-evolution), and Billion Sea Dragon Beast.