Kosei
given name · Latin script
Recorded as a male name· opposite-gender records fall within measured source noise
/koʊseɪ/(machine-generated) pronunciation, model-generated
Kosei is a given name written in the Latin script, with more bearers in Japan than in any other country.
- JPJapan≈1 in 12K(inferred from the name graph)
- AUAustralia≈1 in 1.3M
- SGSingapore≈1 in 1.5M
carrying the name, as counted by its national register where one exists and as Mondonomo estimates it elsewhere (marked ≈ and "est." on hover). One hue, darker where it is more common; hover a country for its figure.
- Japan (inferred from the name graph)
- Sources
- 91 (measured from records)
- ≈1 in 12K (inferred from the name graph)
≈10,000 people, est.
Highest-authority source
Japan, est.
measured from records inferred from the name graph
Meaning & origin
No verified etymology recorded for this name yet — the entries below are drawn from usage statistics and the name graph.
Attested in 1 language in the etymology graph.
Where in the world(measured from records)
Kosei counted together with the spellings and other-language forms grouped with it. Where a register counted another spelling, the row names it.
Sorted by bearers: national registers' counts, and Mondonomo's estimates (≈, est.) where no register counts.
| Country | Most common spelling | Sources | |||
|---|---|---|---|---|---|
| JP Japan | ≈10,000 est. | ≈1 in 12K | — | Kosei | 91 |
| US United States | ≈71 est. | ≈1 in 4.7M | 7 | Kosei | 72 |
| KE Kenya | ≈23 est. | ≈1 in 2.3M | — | Kosei | 4 |
| AU Australia | ≈19 est. | ≈1 in 1.3M | 1 | — | — |
| BR Brazil | ≈14 est. | ≈1 in 15M | 22 | — | — |
| PL Poland | 6 | 1 in 6.4M | 9 | — | — |
| CL Chile | ≈5 est. | ≈1 in 3.5M | 1 | — | — |
| SG Singapore | ≈4 est. | ≈1 in 1.5M | — | Kosei | 5 |
Exact figures are national registers' own counts, while figures marked ≈ and est. are Mondonomo’s estimates, counted from our sources and calibrated against those registers; hover one for how far to trust it in that country. A dash means neither exists.
Registers cited: SSA — National Baby Names (1880–present); Brasil.IO genero-nomes (IBGE Censo 2010 mirror, CC-BY-SA); dane.gov.pl — PESEL given names (first + second name position, 2026-01-20); dane.gov.pl — PESEL living persons (surnames); SRCEI — Nombres más comunes (guaguas, 1920–2021); SA BDM — Popular baby names South Australia (1944–present). Figures without a register are Mondonomo estimates; see Methodology.
Country figures for a list of names, at full precision, are available under licence rather than by scraping this table (how that works).
Notable people with this name(measured from records)
- Kōsei Saitōb. 1932JPJapanese film director (1932-2012)
- Kōsei Tomitab. 1936JPJapanese actor, voice actor and narrator (1936-2020)
- Kōsei Onob. 1939JPJapanese translator and film critic
- Kōsei Hirotab. 1951JPJapanese voice actor
- Kosei Kitauchib. 1974JPJapanese association football player
- Kōsei Inoueb. 1978JPJapanese judoka
- Kousei Amanob. 1978JPnot in their usual nameJapanese actor
- Kosei Nakamurab. 1981JPJapanese association football player
- Kosei Shibasakib. 1984JPJapanese association football player
- Kosei Tanib. 2000JPJapanese association football player
The ten people covered by the most Wikipedia language editions — a proxy for cross-cultural notability, which favours historical and Western figures over equally prominent contemporary ones — shown by birth year. Source: Wikidata (CC0).
How to address them(machine-generated)
A formal English salutation is built on the surname, so it needs a full name — on its own, a first name only supports the informal form.
Evidence(measured from records)
Attested in 13 sources across 8 countries.
| Country | Register | Year | Count | Rank |
|---|---|---|---|---|
| BR Brazil | Brasil.IO genero-nomes (IBGE Censo 2010 mirror, CC-BY-SA) | — | 22 | #47,526 |
| US United States | SSA — National Baby Names (1880–present) | 2008 | 9 | — |
| US United States | SSA — National Baby Names (1880–present) | 2020 | 7 | — |
| PL Poland | dane.gov.pl — PESEL given names (first + second name position, 2026-01-20) | 2026 | 6 | #15,342 |
| US United States | SSA — National Baby Names (1880–present) | 2018 | 6 | — |
| US United States | SSA — National Baby Names (1880–present) | 2013 | 6 | — |
| US United States | SSA — National Baby Names (1880–present) | 2010 | 6 | — |
| US United States | SSA — National Baby Names (1880–present) | 2009 | 6 | — |
| PL Poland | dane.gov.pl — PESEL living persons (names) | — | 5 | #15,809 |
| US United States | SSA — National Baby Names (1880–present) | 2019 | 5 | — |
| US United States | SSA — National Baby Names (1880–present) | 2016 | 5 | — |
| US United States | SSA — National Baby Names (1880–present) | 2014 | 5 | — |
Reference works 2
- Dictionary of American Family Names
- Wikipedia surname tokens
These works list the name; their figures are licensed and are not reproduced here.
Register rows as of the 2026-10-09 data build.
Frequently asked questions
- How do you pronounce Kosei?
- A machine transcription gives /koʊseɪ/ (IPA) for Japanese.
- Is Kosei a male or female name?
- Kosei is a male name in our records. Opposite-gender entries fall within the cross-gender noise we measure in the source data, so we don't report them as usage.
- In which country does Kosei have the most bearers?
- Mondonomo estimates about 10 thousand people named Kosei in Japan, more than in any other country we hold, where it is most often spelled kosei.
- How common is the name Kosei?
- In Poland, the national register counted 6 people named Kosei in 2026, about 1 in 6.4 million residents.
What do you want to know about Kosei?
Nobody replies to these one by one, but what readers ask decides what these pages answer next.
Query this name via API
curl -H "X-API-Key: YOUR_KEY" https://api.mondonomo.ai/api/v1/name-graph/koseiThe payload this page is built from: spellings and scripts, countries and languages, related names, and the registers that attest the form. It takes a free API key (1,000 requests a day), which returns what this page shows everyone; the full country table, every register citation and the year-by-year series come with a licensed key, as does bulk access.
About this data
measured from records inferred from the name graph machine-generated
These figures come from the data snapshot of and will change as it is rebuilt.
Statistics are aggregated from the Mondonomo name corpus; related names and etymology are inferred from the name graph; pronunciation and any machine-marked transliterations are model-generated. Read how the numbers are made, including their known failure modes, and where the data comes from.
Reference works we consult — surname dictionaries, official name registers, Wikidata and Wiktionary — are named directly, beside the claims they support. The per-country source counts also include datasets of person records: we publish how many there are and their authority tier, but not their names.
Cite this page Mondonomo, “Kosei”. Data snapshot 2026-10-10.