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Sonic News Network
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Metal Sonic Kai[1] is a transformation that appears in the Sonic the Hedgehog series. It is a transformation of Metal Sonic caused through exposure to a large Dark Ring.[1] Metal Sonic Kai appeared during the Newtrogic High Zone incident, where he attempted to destroy Knuckles and his teammates upon the orders of Dr. Robotnik, only to be defeated.


Metal Sonic Kai has a similar appearance to his base form as Metal Sonic, although he is much bigger, more monstrous-looking and red in color. The quills, "ears", and spines on his back are long and sharp. Metal Sonic Kai also has separated eyes that are similar to a visor, with a long, sharp nose located between them. Additionally, he has a large mouth, with sharp metal teeth inside. On his torso, he has a black circular depression with a yellow bulb. His arms and legs are separated from his torso. There are also some exposed tubes on his body.


Knuckles' Chaotix

In Knuckles' Chaotix, after his last fight, a heavily damaged Metal Sonic came to rest in front of Dr. Robotnik. With his large Dark Ring, Robotnik restored Metal Sonic as Metal Sonic Kai, who proceeded to attack Knuckles and his crew. Despite commanding the power of his newfound transformation however, Metal Sonic Kai was defeated by the heroes.

Powers and abilities

Metal Sonic Kai using the Plasma Pulse Attack, from Knuckles' Chaotix.

As Metal Sonic Kai, Metal Sonic is capable of flight despite his massive frame. He can also fire powerful laser beams from the bulb in its torso, similar to the Plasma Pulse Attack.


Metal Sonic Kai is the second boss of the World Entrance in Knuckles' Chaotix, and the eighth and final overall boss of the game. He is encountered with either Knuckles, Vector, Espio, Charmy, Mighty, Heavy or Bomb.

Boss guide

The boss fight takes place in a square-shaped room. It is divided into three phases with Metal Sonic Kai:

  • In the first phase, Metal Sonic Kai will be located to the right side of the boss field and will try to attack the playable character with his hand. The player has to hit him eight times to proceed to the second phase.
  • In the second phase, Metal Sonic Kai will be located in the background of the boss field. He will try to crush the playable character with one of his hands. The player has to hit his hand while attacking another eight times to destroy it.
  • In the third and final phase, Metal Sonic Kai will be located to the left side of the room. He will then charge the Plasma Pulse Attack with his bulb and fire it towards the other side. Touching the laser will damage the playable character. While Metal Sonic Kai is not charging his laser, the player has to hit the bulb eight times to defeat him.


Name Artist(s) Length Music track
"Oriental Legend" Junko Shiratsu, Mariko Nanba 1:09

In other media

Sonic the Comic

Main article: Emperor Metallix

In the Sonic the Comic comic series published by Fleetway Editions, a similar robot to Metal Sonic Kai called Emperor Metallix makes an appearance. He was the leader of the Brotherhood of Metallix, created by the robots themselves.

Archie Comics

Titan Metal Sonic, from Sonic Universe #65.

In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, Metal Sonic Kai is referred to as Titan Metal Sonic. The first Titan Metal Sonic that appeared was a transformation of Metal Sonic v2.0, which he achieved with a Power Gem. However, he was defeated by Knuckles. The next incarnation to appear would be a rebuilt model made by Dr. Eggman as the ultimate attack robot, which he would begin deploying in the aftermath of Operation: Clean Sweep.

After the Super Genesis Wave re-wrote history, Titan Metal Sonic acquired the same history as its video game counterpart.


  • In the Japanese Chaotix instruction manual, the name Metal Sonic Kai (メタルソニック改 Metaru Sonikku Kai?) refers to the blue, regular-sized version of Metal Sonic, whose main and sub CPUs had been put into a spare body and was reborn with Dark Ring power. This body was also installed with a "Plasner," enabling the Plasma Pulse Attack.[2] The Japanese version of Sonic Gems Collection also names the blue, regular sized version of the robot "Metal Sonic Kai" in artwork no. 160 in the Museum.[3] However in the Sonic the Hedgehog Encyclo-speed-ia book though, the name "Metal Sonic Kai" is used to refer to a crimson behemoth fought at the end of Knuckles' Chaotix.[1] This was not a mistake but rather a revision of information.[4]
  • By hacking into Knuckles' Chaotix, it is possible to find an unused sprite of Metal Sonic Kai's head with several tubes hanging from his neck area.
  • According to some unused sprites of Metal Sonic Kai, there were originally more attacks planned for him, such as shooting out smaller lasers or bullets.
  • Giga Metal, a transformation that appears in Sonic Mania Plus, greatly resembles Metal Sonic Kai.


  1. 1.0 1.1 1.2 1.3 Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. p. 70. ISBN 978-1506719276. "Metal Sonic takes control of the stage roulette. Stop the selector on X to destory one of Metal Sonic's options. Otherwise, you'll choose the manner of your own demise. Restored by a massive Dark Ring, the crimson behemoth Metal Sonic Kai attempts to crush you with its massive claws and fry you with his giant laser."
  2. Chaotix (Super 32X) Japanese instruction booklet, pg. 43.
  3. Sonic Team (11 August 2005). Sonic Gems Collection. Nintendo GameCube. Sega. Area/Level: Museum, Artwork no. 160.
  4. BumbleKast Priority Q&A for December 20th, 2021 (1:19:35). YouTube (20 December 2021). Retrieved on 19 March 2022.

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