Dr Muscle is a mysterious masked wrestler in Dragon Gate who wears a jumpsuit and white lab coat covered in (what appears to be) blood. During late January/early February 2017, many called the Dr. Muscle aligned with the VerserK unit Dr. VerserK, however this was a dubbed title by Jae of iHeartDG and isn't his cannon name during that time.
Originally this was a gimmick planned for T2P graduate and former Florida Brother, Raimu Mishima. However, Raimu was forced into retirement due to injuries.
Despite this, Dr Muscle continued to show up in Muscle Outlaw'z matches. The reality is that many different wrestlers have been donning the Dr Muscle outfit. The clue is usually which of whatever team he is aligned with is missing from ringside when he appears.
Due to this fact though, many wrestlers have used the Dr Muscle outfit to double-cross his team, usually unmasking after the fact. He has also been used to disguise the return, or eventual alliance turns of wrestlers (such as most recently Kzy's defecting from MAD BLANKEY to Dia. Hearts & Kotoka's turning on VerskerK's newest members only to be kicked out himself). Naruki Doi used the guise to reform his alliance with Masato Yoshino. Gamma used the guise to join Junction Three after drawing similarities between his Open the Gamma Gate reign and Naoki Tanizaki's Blood Warriors Authorized Brave Gate reign, with Gamma's major gripe being Gamma having won the belt in his run where as Tanizaki simply stole his while PAC was out of the country.
As a general rule, Dr Muscle is always aligned with whatever the heel faction is in Dragon Gate at the time. He also tends to use miscellaneous moves of Dragon Gate wrestlers, even if they've got an alibi to not being Dr Muscle, to hide his actual identity. Following Muscle Outlaw'z disbanding, Dr. Muscle vowed to carry on the MO'z name until the end of time, including their theme, Idiot Outlaw.