Japan Internal Combustion Engine Industry, Hiroshima, 1949-59
This is actually quite an old company which is still in business and that goes back to 1917 operating under several different names. Beginning in 1927 they made 3 wheeled vehicles first called New Era (ニューエラ) which were renamed JAC (ＪＡＣ号) which was again changed in 1932 to the Kurogane (ろがね or 鉄 which is an old name for iron) brand name. The brand name 'Kurogane' then was applied the other products made by Japan Internal Combustion. During WWII the company produced military vehicles which included the Kurogane Type 95 military motorcycle which was a derivative of the Rikuo 97 which in turn was originally a licensed copy of the Harley-Davidson JD 74. In 1957 it changed its name to Tokyu Kurogane Industry (東急くろがね工業) and eventually in 1962 completely withdrew from the sale of complete vehicles becoming a engine and parts supplier for the Nissan Motor group of companies. Most of this information is available on the Japanese Wikipedia site at this link, as well as in a document called 'History of the KUROGANE Military Vehicles of Japanese Army' (日本内燃機 “くろがね” 軍用車両史) which you can download in PDF format from this link.
The plant making the Kurogane Type 95 machine was in Hiroshima and largely destroyed by the nuclear bomb attack on August 6, 1945. As well during the occupation that followed after the cessation of hostilities, most of Japan's military equipment was destroyed, so examples of the Kurogane Type 95 are quite rare. There is one in the USA that has been redone as a civilian version, although these were never offered for civilian use. There is one restored military version in Russia, as well as perhaps a few in Japan (one is supposedly in the Fukuyama Automobile Watch Museum in Japan) .
Three wheeled production did continue at their other facilities, as well as the manufacture of a bolt on moped kit for bicycles called the Panky (パンキー号). This was a 62cc 2 stroke putting out 1 HP at 3000 RPM. Unfortunately I have not been able to find a single photo of it, nor do I have information on how long it was available, but it is described on page 266 of the 'History of the KUROGANE Military Vehicles of Japanese Army' (日本内燃機 “くろがね” 軍用車両史) document. Also described on the same page is a prototype 500cc twin developed in 1955 called the BA500 which did not go into production, but did evidently survive and was profiled in Japan's MotorCyclist magazine. The BA500 was designed by Yoshio Nakamura who later joined Honda and eventually became their F1 team manager.
This is a video produced by the Russian MotorWorld Museum showing the Type 95.