Last name 研一 (Kenichi 
, 研一 , Ken'Ichi ) , around the globe, is quite a common cognomen. The last name 研一 is characteristic of Japan, where it is quite a rare surname, Taiwan, and Singapore, where it is a rare surname. Measured by absolute frequency, it most frequently occurs in Eastern Asia, particularly Japan, China, and Taiwan. Also, 研一 is the forename as well as the last name.