Yamaguchi Bicycle was a bicycle manufacturer, founded by Shigehiko Yamaguchi in 1914 in Tokyo, Japan. In 1963 the company went bankrupt and was bought out by Marubeni and rechristened 'Marubeni Yamaguchi'.

Marubeni was founded in 1858 also in Tokyo, Japan. It is one of the famous five zaibatsu - giant, conglomerate, trading companies that dominated the Japanese economy for much of the 20th century. Even today the decendants of these five companies remain big players. Wikipedia lists Marubeni's current areas of business as being merely 'food, textile, paper, chemicals, energy, metal, transportation machinery, industrial machinery, electricity, plants, ships, finance, logistics and steel'.

In 1982 Marubeni sold the business to Sekine, another bicycle manufacturer. And in 1986 the business was sold on by Sekine to become an independant company again - now called Asahi Cycles.