Tokyo Motor Co., Ltd., Tokyo, 1948-66
This company has its roots in the Takata Motor Research Institute of 1922 which began building engines for fire pumps, radio generators and marine applications. As Takata Motor Production Company (タカタモーター製作株) they also developed the first Japanese outboard engine in 1935, which was a two cylinder, 3 HP two stroke.
Post WWII, it reformed as Tokyo Motor and started to produce motorcycle engines, both for itself and for other companies, under the Tohatsu (トーハツ号) brand. Immediately post war, the focus was on small 2 stroke clip-on engines for bicycles, and then moving into mopeds and actual motorcycles. Tohatsu produced a number of leading edge engines for racing, including a 50cc two stroke twin with rotary valves that produced 11 HP at 13,500 RPM in 1964. Hap Jones Distributing imported the Tohatsu product line into the USA in 1963 and 1964 (per "The Tiddler Invasion', page 208). However since peaking in 1955 from a market share perspective, Tokyo Motor mis-judged the domestic market, were not successful with the export market and so eventually filed for bankruptcy in 1964. Bridgestone supposedly benefited from the sudden availability of skilled two stroke engineers, and if rumour can be believed the Tohatsu rotary valve technology was incorporated into the Bridgestone machines introduced in the mid-1960's.
After exiting the motorcycle business, Tokyo Motor refocused on outboard marine engines and fire pumps and today as Tohatsu Corporation (トーハツ株式会社) are one of the larger outboard marine manufacturers in the global market, supplying engines for Mercury and Nissan. There is an excellent corporate history on their web site, in English, at this link.