Ryusei Tsurugi

"Wind, Clouds, Sun! I ask you from the bottom of my heart- why was I born in the world like this?! (風よ、雲よ、太陽よ!心あらば教えてくれ. なぜ、この世に生まれて来たのだ?! Kaze yo, kumo yo, taiyō yo! Kokoro areba kotaetekure. Naze, kono sekai ni umaretekitanoda?!)"

- Metalder after his first fight with Coolgin.

Metalder (メタルダー) is a "Choujinki", a powerful war android built by Dr. Koga at the end of World War II originally as a countermeasure against the Americans. He was hidden in a secret base of the Japanese Imperial Army until Dr. Koga activated him years later to fight the Neros Empire. Whenever his energies reach a peak from rage, with the cry "Ikaru!" (怒る!), he transforms into his metallic form. Powered by 'super-gravitational energy', his killing techniques include "Laser Arm", "G-Kick", "Metal Tornado" spinning kick, "Head Crash" ram, "Plasma Punch", "Metal Bomber" punching attack from above, And "1000 Hand Punch".

Choujinki Metalder
He was hidden in a secret base of the Japanese Imperial Army, the Silver Carcass, until Dr. Koga activated him years later to fight the Neros Empire.

Metalder lived in the Silver Carcass with Springer, a dog that was able to speak through a machine created by Dr. Koga. He had a human guise known as Ryusei Tsuguri. His two friends were Mai Ogi and Hakko Kita who both became aware that he was Metalder shortly after meeting him.

At the end of the series he defeats God Neros but in the process, his super-gravitational energy is greatly damaged, as a result whenever he moves longer, he will explode and the world will be destroyed by its impact. With Kita's help, Metalder is spared from destruction, but at the cost of his human form and his ability to fight as a Choujinki.

In a stage show where the are seen fighting their usual foes, the Armored Army and  show up and wind up defeating them. Metalder and arrive and assist the Maskmen.

In a stage show where the Maskman are seen fighting the, Kamen Rider Black, Metalder, Spielban, Shaider, & ,  & , , and  arrive and assist the team.

In a stage show where the are seen fighting their usual foes,, , Underground Empire Tube, the Armored Army and The Sorcerers Clan show up and wind up defeating them. Kamen Riders Black &, Jiraya, Princess Ninja Emiha, & , Metalder, Red &  and Change Dragon arrive and assist the Livemen.

Personality
His human guise, Ryusei Tsurugi (剣 流星), is directly modeled after that of Dr. Koga's son Tatsuo of whom he lost during the war. Like Tatsuo, he loves music and plays the saxophone from time to time. His Reflection Circuit gave him the same feelings as humans and a sense of right and wrong.

As Tsurugi Ryusei

 * Height: 186cm (73" or 6'1")
 * Weight: gravity control to more than 100kg (220 lbs)
 * Time for 100 m run: 11 sec.

As Chojinki Metalder

 * Height: 190cm (75" or 6'3")
 * Weight: 250kg (551 lbs)
 * Time for 100m run: 1.5 seconds
 * Jump height: 150 metres (164 yards)
 * Punch Power: 10 cm(4 inches) through an iron board
 * Kick power: breaking an 20cm (8 inches) iron pole

Techniques
 * Laser Arm
 * G-Kick
 * Jumping Distance
 * Iron Claw
 * Vacuum Adhesion Apparatus
 * Metal Tornado
 * Plasma Punch

Arsenal

 * Silver Carcass
 * Side Phantom
 * Metal Charger

Ranger Key
The Metalder Key (メタルダー) is a Metal Heroes released as part of the Ranger Keys Metal Hero Edition in Bandai Premium. It is unknown if it will appear in a future crossover. Of course as with all Ranger Keys, should it exist, it would be able to one, i.e. one of the, into Metalder.

Portrayal
Ryusei Tsurugi is portrayed by Seikō Senō (妹尾 青洸) (credited as Akira Senō (妹尾 洸)), who also portrayed Tatsuo Koga. As Metalder, his suit actors were Kazuyoshi Yamada (山田 一善) and Noriaki Kaneda (金田 憲明).