2000
#140,756
National surname rank
Recorded bearers 109
First available Census row
Per 100,000 0.04
Very Rare Last name
Kumai
An uncommon surname possibly derived from the Japanese word for "cloud".
According to the 2020 US Census Bureau surname tables, roughly 130 Americans carry the last name Kumai. That puts it at #147,221 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,636,572 residents).
This page is the full Name Census profile for the Kumai surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
Bearers in the US
130
1 in 2,636,572
Census rank
#147,221
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
113
very rare in the US
Popularity narrative
The Census Bureau recorded 113 bearers of the surname Kumai in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 147221st position in the national surname ranking.
Among Census respondents with the surname Kumai, the largest self-reported group is Asian/Pacific Islander at 81.4%. The next largest groups are Two or More Races (7.1%) and Hispanic (5.3%).
Origin
Meaning and origin of Kumai
The surname KUMAI originates from Japan, with roots dating back to the 8th century AD. It is believed to have derived from the Old Japanese word "kumagai," which means "eternal" or "everlasting." This name was initially concentrated in the regions of Honshu and Kyushu, where it was adopted by several noble families during the Heian period (794-1185).
One of the earliest known references to the KUMAI name can be found in the Shoku Nihongi, an early 9th-century historical text that chronicles the lives of Japanese emperors and nobility. The text mentions a prominent samurai warrior named Kumai no Takahiro, who served under the Imperial Court during the reign of Emperor Kammu (737-806).
In the 12th century, the KUMAI name appeared in the Heike Monogatari, a famous Japanese epic that recounts the struggle between the Taira and Minamoto clans for control of the Imperial Court. The text mentions a skilled archer named Kumai no Yoshitsuna, who fought bravely in the Battle of Ichi-no-Tani in 1184.
During the Kamakura period (1185-1333), the KUMAI family established a prominent presence in the city of Kamakura, which served as the seat of the Shogunate. One notable figure from this era was Kumai no Masatsugu (1170-1252), a renowned Buddhist monk and calligrapher who studied under the famous Zen master Dogen.
As the centuries passed, the KUMAI name spread throughout Japan, and several notable individuals emerged. In the 16th century, Kumai Kotora (1537-1594) was a skilled swordsmith who crafted blades for many samurai warriors during the Sengoku period.
Another prominent figure was Kumai Tokinosuke (1699-1771), a influential merchant and financier who played a crucial role in the economic development of Edo (present-day Tokyo) during the Tokugawa shogunate.
In more recent times, Kumai Kiyoshi (1878-1949) was a renowned painter and printmaker who helped popularize the Japanese woodblock printing technique known as ukiyo-e during the Meiji and Taisho periods.
Throughout its long history, the KUMAI name has been associated with various place names and older spellings, such as "Kumagai," "Kumae," and "Kumae-no-sho." These variations reflect the linguistic and cultural diversity of Japan's regions, as well as the evolution of the Japanese writing system over time.
Demographics
Ancestry and ethnicity for Kumai
Among Census respondents with the surname Kumai, the largest self-reported group is Asian/Pacific Islander at 81.4%. The next largest groups are Two or More Races (7.1%) and Hispanic (5.3%).
The bar chart below shows how Kumai bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Kumai surname at the time of the 2020 Census, not any inherent property of the name itself.
- Asian and Pacific Islander81.4% · 92
- Two or more races7.1% · 8
- Hispanic or Latino5.3% · 6
- White3.5% · 4
- Black or African American2.7% · 3
Timeline
Historical Census data for Kumai
Kumai appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#142,108
National surname rank
Recorded bearers 117
+8 bearers (+7.3%)
Per 100,000 0.04
Rank movement Down 1,352 places
2020
#147,221
National surname rank
Recorded bearers 113
-4 bearers (-3.4%)
Per 100,000 0.04
Rank movement Down 5,113 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #140,756 | 109 | 0.04 | First available Census row | First available Census row |
| 2010 | #142,108 | 117 | 0.04 | +8 bearers (+7.3%) | Down 1,352 places |
| 2020 | #147,221 | 113 | 0.04 | -4 bearers (-3.4%) | Down 5,113 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Kumai surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #142,108 | #147,221 | -3.6% |
| Count | 117 | 113 | -3.4% |
| Per 100K | 0.04 | 0.04 | -5.5% |
Between the 2010 and 2020 Census, the number of Kumai bearers went from 117 to 113 (-3.4% change). The surname moved down 5,113 positions in the national ranking, going from #142,108 to #147,221.
FAQ
Kumai surname: questions and answers
How many people in the U.S. have the surname Kumai?
Name Census estimates that about 130 living Americans carry the surname Kumai. Using the current population baseline, that works out to roughly 1 in 2,636,572 residents.
How common is Kumai?
Kumai ranks #147,221 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.04 per 100,000 residents, which is about 0 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 113 people with the surname Kumai. That is different from the site's living-bearer estimate (130), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.04 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.04 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 0 of them to have the surname Kumai.
Has Kumai become more or less common over time?
Between 2010 and 2020, the surname Kumai went from 117 recorded bearers to 113. That is a decrease of 4 (-3.4%). In the national ranking it fell from #142,108 to #147,221.
What does the Census say about the background of Kumai?
Among Census respondents with the surname Kumai, the largest self-reported group is Asian/Pacific Islander at 81.4%. The next largest groups are Two or More Races (7.1%) and Hispanic (5.3%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
Asian/Pacific Islander is the largest self-reported group for the surname Kumai in the 2020 Census, accounting for 81.4% (92 people in the source table).
What is the full ancestry breakdown?
Kumai appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are Asian/Pacific Islander (81.4%), Two or More Races (7.1%), Hispanic (5.3%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Kumai (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Kumai mean?
An uncommon surname possibly derived from the Japanese word for "cloud". The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Kumai (0.04 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people are called Kumai?
Want to know how common the surname Kumai is? HowManyOfMe.org, our sister site, puts the living-bearer count front and centre.