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Metal Sonic Kai[2] 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.[2] 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.

Quick Answers

What transformation does Metal Sonic undergo to become Metal Sonic Kai? toggle section
The transformation of Metal Sonic into Metal Sonic Kai is triggered by exposure to a large Dark Ring. This event took place during the Newtrogic High Zone incident. As Metal Sonic Kai, he grows significantly larger, his body changes to red, and his Plasma Pulse Attack becomes more potent. He tried to destroy Knuckles and his team under Dr. Robotnik's command, but was ultimately defeated.
Provided by: Fandom
What event led to the appearance of Metal Sonic Kai in the Sonic the Hedgehog series? toggle section
The appearance of Metal Sonic Kai in the Sonic the Hedgehog series was triggered by exposure to a large Dark Ring. This transformation occurred during the Newtrogic High Zone incident. Under Dr. Robotnik's orders, Metal Sonic Kai attempted to destroy Knuckles and his team but was ultimately defeated.
Provided by: Fandom
Who does Metal Sonic Kai attempt to destroy upon the orders of Dr. Robotnik? toggle section
Dr. Robotnik orders Metal Sonic Kai to destroy Sonic and the Land of the Sky. To make Metal Sonic Kai the ultimate fighting machine, Dr. Robotnik infuses it with Sonic's life data. Sonic is tricked into coming to Robotropolis, where his life data is downloaded. Metal Sonic Kai also attacks Knuckles and his crew after being restored by Dr. Robotnik.
Provided by: Fandom
How does the appearance of Metal Sonic Kai differ from his base form as Metal Sonic? toggle section
Metal Sonic Kai, a variant of Metal Sonic, is significantly larger and sports a red hue. His features, including quills, 'ears', and spines, are elongated and sharp. His eyes resemble a visor, separated, and his nose is long and pointed. This transformation was first seen in the Newtrogic High Zone incident featured in Knuckles' Chaotix.
Provided by: Fandom
What causes Metal Sonic's transformation into Metal Sonic Kai? toggle section
The transformation of Metal Sonic into Metal Sonic Kai is triggered by exposure to a large Dark Ring. This event took place during the Newtrogic High Zone incident. Under Dr. Robotnik's command, Metal Sonic Kai attempted to obliterate Knuckles and his team but was ultimately defeated.
Provided by: Fandom

Concept and creation[]

During the development of Knuckles' Chaotix, Ryo Kudou was tasked with designing Metal Sonic Kai, although due to complications Kudou asked for Takumi Miyake to design it instead.[1] As such, Miyake created the design for Metal Sonic Kai, while Kudou used Strata 3D to translate the design into a 3D model, and then drew over that model to create the sprites.[3]

Although Ryo Kudou and some of his programmer friends wanted the robot to be named Devil Sonic after the Devil Gundam from the anime series Mobile Fighter G Gundam, game designer Kenichi Ono insisted upon the robot being named Death Metal Sonic.[4]

Possibly due to this naming confusion, the robot's name would be officially revised as Metal Sonic Kai in the 2021 Sonic the Hedgehog Encyclo-speed-ia[2][5], taking its name from the regular Metal Sonic seen throughout the game, which was referred to as "Metal Sonic Kai" in early Japanese sources. Said robot was also renamed to simply "Metal Sonic" to avoid additional confusion with its giant crimson transformation.

Appearance[]

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.

History[]

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[]

Easily avoidable laser

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.

Battle[]

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.

Music[]

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 SU65

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.

Trivia[]

  • 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.[6] 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.[7] 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.[2] This was not a mistake but rather a revision of information.[5]
  • 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.

References[]

  1. 1.0 1.1 Ryo Kudou on Twitter. Twitter (12 July 2025). Retrieved on 12 July 2025. "Ryo Kudou: 作画は私、デザイン担当は三宅巧巳君です。本来は作画担当の僕がデザインするべきだったのですが、どうにもできなかったのでお願いして描いてもらいました。"
  2. 2.0 2.1 2.2 2.3 2.4 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."
  3. Ryo Kudou on Twitter. Twitter (12 July 2025). Retrieved on 12 July 2025. "Ryo Kudou: 作画工程は、形の基本をStrata 3Dでモデリングし、レンダリングした画像をメガドラカラーに減色し、あとはドット絵として、3Dに見えるように細部の形を描き込んでいきます。3Dモデリングした画像は、おおまかな光の方向と色彩以外、ほぼ残っていません。"
  4. Ryo Kudou on Twitter. Twitter (12 July 2025). Retrieved on 12 July 2025. "Ryo Kudou: 僕とプログラマー達はこのメカのことを、『Gガンダム』に登場する敵メカの名前に倣い「デビルソニック」と呼んでいました。 企画の小野くんが「デスメタルソニックだ!」と主張しても、僕らは全く聞いていませんでした。 ゲーム添付の説明書に何という名前で紹介されていたのかは知りません。"
  5. 5.0 5.1 BumbleKast Priority Q&A for December 20th, 2021 (1:19:35). YouTube (20 December 2021). Retrieved on 19 March 2022.
  6. Chaotix (Super 32X) Japanese instruction booklet, pg. 43.
  7. Sonic Team (11 August 2005). Sonic Gems Collection. Nintendo GameCube. Sega. Area/Level: Museum, Artwork no. 160.

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