Koichi has been given to about 145 people in the United States since 1880. It was most common in 1921, which makes it a interwar name.
Its best year was 1921, when 16 babies were given the name, ranking 2110th. The typical living American called Koichi is about 38 years old today.
Source: US Social Security Administration, national and state name files, 2025 release. Etymology researched and written by our editors. Living-population and median-age figures are our own estimates, described in the methodology.