Officially, among Japanese names there are 291,129 different Japanese surnames (姓, sei),[1] as determined by their kanji, although many of these are pronounced and romanized similarly.
Conversely, some surnames written the same in kanji may also be pronounced differently.
[2] The top 10 surnames cover approximately 10% of the population, while the top 100 surnames cover slightly more than 33%.
[3] This ranking is a result of an August 2008 study by Meiji Yasuda Life Insurance Company,[3] which included approximately 6,118,000 customers of Meiji Yasuda's insurance and annuities.