Sumitomo Masatomo (住友政友,
Sumitomo Masatomo) (31 December 1585–17 September 1652) was a
Japanese copper mining businessman. He was the founder and
eponym of
Sumitomo Group. Originally he was a Buddhist monk. During his lifetime, there were mainly two sectors of Buddhist monks in Japan. Masatomo belonged to one sector, which ceased to exist later. Reluctant to join the other group of Buddhist monks, he turned to business to make a living. He started his business by selling books and medicines at first, in a bookshop in Kyoto circa 1615.