Chojinki Metalder (超人機メタルダー,Chōjinki Metarudā?, Superhuman-Machine Metalder) is the sixth and shortest entry of the Metal Hero Series, running from March 16, 1987, to January 17, 1988, for only 39 episodes. Toei went for a darker and more grim direction for Choujinki Metalder, and this turned off younger viewers. As a result, ratings started to slip in the second half, and the series ended after just 39 episodes, making it the shortest Metal Hero series.
Originally, the action footage of Metalder was going to be adapted for the unpiloted show, Cybertron, starring Jason David Frank from Mighty Morphin' Power Rangers but was then canceled. Later, they reused the same footage for the first season of VR Troopers.
For distribution purposes, Toei refers to this television series as Metalder. On February 21, 2007, Toei released the complete Metalder TV series and film on a seven-disc DVD set.
In 1945, Dr. Ryuichiro Koga designed Metalder as a top-secret weapon for the Japanese Imperial Army for use in the Pacific War, modeling it after his late son, Second Sub-lieutenant Tatsuo Koga. However, the pacifistic Dr. Koga put Metalder to sleep in the Silver Carcass base and left for America to work for NASA. During the 42 years, Dr. Koga's former colleague Major Muraki became the evil God Neros, ruler of Neros Empire. God Neros sends out his massive armies to kill Dr. Koga, who learned of their organization and returned to Japan to activate Metalder. Koga desperately tries to activate his android creation, who he named Ryusei Tsurugi, but the android is unable to understand what to do. In order to give Ryusei a "purpose", Koga runs out of the Silver Carcass base, allowing Neros' troops to kill him. Suddenly seeing his creator die, Ryusei becomes shocked, and soon is beaten by Neros' troops. Ryusei becomes fueled with rage, evoking the conversion to his 'true' form, the android known as Metalder. After a brief battle with Coolgin (which he loses), Ryusei goes onward, meeting future friend Mai Ogi.
In its home country of Japan, Toei Video released the series on VHS from January 1991 to September 1992. 7 volumes were released as only up to 21 out of 39 were made available in this format. The reason why it was released half-finished and in the middle, had nothing to do with the popularity, but there was a change in Toei Video's policy at the time, as it was being released around the same time it was implemented. Space Sheriff Shaider and MegaBeast Investigator Juspion were also stopped midway. Instead, they decided to start doing full releases of newer works, starting with Chōjin Sentai Jetman. Years later on February 21, 2007, all 39 episodes and the movie were released on home video for the first time on DVD in a seven-disc Boxset.
In Thailand, the series aired on Channel 3 with a Thai dub on Sunday Mornings from 1989-1990 as Superhuman Robot Metalder. (ยอดมนุษย์หุ่นยนต์ เมทัลเดอร์)
In the Philippines, it was given a Tagalog dub and aired on ABS-CBN from 1990 to 1991.
In France, the series aired as simply Metalder on TF1's Club Dorothee block on July 24, 1989. It was licensed by AB Groupe and Studio SOFI produced a French dub for the series to air, and all episodes were covered. It was also released on VHS in the 1990s by Dagobert Vidéo (AB Groupe's video brand).
In Brazil, it was given a Brazilian Portuguese dub and aired as Metalder, o Homem Máquina (meaning Metalder, the Machine Man) on Rede Bandeirantes from April 21 to December 21 of 1990.
In Hong Kong, the series was given a Cantonese Chinese dub and aired on TVB Jade as Silver Warrior (銀戰士Yín Zhànshì), on November 22, 1994.
Both Metalder and Kamen Rider Black are heroes that don't have their own weapons in their disposal and rely only on physical attacks.
In the French dub of Choujinki Metalder, the entire music score by Seiji Yokoyama was replaced with musical pieces by Shuki Levy, who also worked with Saban Brands. However, Episode 17 and 18 kept the saxophone variant of the original Metalder theme song.