Family name Коити (Koichi 
, Коити, Kōichi) , across the world, is a common last name. The cognomen Коити is characteristic of Japan, where it is quite a rare surname, Taiwan, and Singapore. Not in comparison with a country's population, it is the most numerous in Eastern Asia, particularly Japan, China, and Taiwan. Likewise, Коити is the forename as well as the last name.