too much gel is extracted, the person becomes comatose and may even die. On the other hand, gel is a powerful medicine that can heal anything. If a healthy person is injected with Gel they become stronger than a normal human, as is the case with Sergei. Dr. Mima discovered that Gel may be used as power source and control mechanism for robots, but once he learned the truth about the gel extraction process he halted his research on moral grounds, something which Ajo was not happy about. Ajo Heavy Industries collects gel from human sources, such as homeless people or enemies of the company, in order to fuel PPORs. Mima Formula A set of principles or rules for the construction and operation of robots, based on Gel as a kind of fuel and control mechanism. The basic principle is that gel can be extracted from a person and placed into the robot. The gel then powers the robot and also allows it to be controlled only by the person who provided the gel. The Mima Formula states that gel that has been extracted from a person will only work with its original owner, and that gel extracted from different people cannot co-exist in the same container. This is why Sergei can control the original PPORs quite well, as they run on the gel from him, and why Ajo's scientists cannot properly operate the PPORs. Release Key the Metal Idol, was originally produced and sold as an "experimental" title, with the original release media (VHS Tapes and LDs) priced very low, at 2,500 yen for a single-episode tape or 5,800 yen for a 3-episode LD, with the first episode retailing at 1000 yen. This was less than half the typical price of OVA titles at the time. As the series progressed, the episode lengths and volume costs continued to increase. The final volumes were priced 9,500 yen each, which was consistent with other titles at the time. The series is also unusual in that the episodes are of varying length. The first thirteen episodes are approximately 25–30 minutes each. The final two episodes are 90 minutes each. In addition to the OVA series, Radio Drama CDs were made. The anime and soundtrack were released in the United States by Viz Video on eight VHS tapes and three DVDs in 1997-2000, and later all together as a box set in 2004.