Seiji
Meaningoften sincere second son · Japanese
Seiji is a Japanese boy name often meaning “sincere second son”. In Japan, parents often choose a name as much for the kanji characters behind it as for its sound, so the same name can carry several shades of meaning. A meaning like this gives a child something to grow into, and a good story to tell when someone asks about their name. It sounds soft and friendly, it's easy to spell and quick to call across a playground, and it pairs well with middle names of almost any length.
Did you know?
- Scrabble scoreIf names were allowed in Scrabble, Seiji would score 12 points, thanks largely to the J (worth 8).
- GenerationSeiji peaked in 1925, which makes it a Greatest Generation name, think great-grandparents. Now it's back in style, so there's a whole new generation of baby Seijis too.
- Roll callIn a typical school of 500 kids, your Seiji would very likely be the only one. About 1 in 212,766 baby boys got the name in 2025.
- HistorySeiji first shows up in US birth records in 1914, the first year at least 5 babies got it. It has been in use for 111 years since.
Save adds it to your list. Vote moves it up the top voted names.
Popularity: U.S. Social Security Administration (babies with 5+ births per year).
About the name Seiji
Seiji is a boy name of Japanese origin meaning “often sincere second son”. Its two syllables give it an easy rhythm, and the open vowel at the end makes it sound soft and warm. It was most fashionable in the 1920s, which gives it a vintage, grandparent-chic charm. It's rarely heard today, so it stands out while still being a real, established name.
Origin:Japanese names
More Japanese boy names
- Unisex name: Asa · healer
- Unisex name: Rio · river
- Unisex name: Akari · light, brightness
- Boy name: Kenzo · often healthy third son
- Boy name: Kenji · often strong second son
- Unisex name: Ren · often lotus
- Unisex name: Zen · meditation
- Unisex name: Mars · god of war
Questions about the name Seiji
What does the name Seiji mean?
Seiji means “often sincere second son” and comes from Japanese. Other boy names with a similar meaning include Sincere (“sincere”), Atsuhiro (“often sincere and broad”), Atsuo (“often sincere man”) and Atsushi (“often sincere”).
What is the origin of the name Seiji?
Seiji is Japanese in origin. Other Japanese names to consider are Asa (“healer”), Rio (“river”), Akari (“light, brightness”) and Kenzo (“often healthy third son”).
Is Seiji a boy or girl name?
Seiji is a boy name. In 2025, 8 US boys were named Seiji.
How popular is the name Seiji?
Seiji ranked #8,910 for US boys in 2025, given to 8 babies. Its best year was 1925, when it reached #2,435. Over the last five years it has slipped 1,408 places.
What names are similar to Seiji?
If you like Seiji, you might also like Sincere, Atsuhiro, Atsuo and Atsushi.
What should I know before naming my baby Seiji?
Seiji is a Japanese boy name often meaning “sincere second son”. In Japan, parents often choose a name as much for the kanji characters behind it as for its sound, so the same name can carry several shades of meaning. A meaning like this gives a child something to grow into, and a good story to tell when someone asks about their name. It sounds soft and friendly, it's easy to spell and quick to call across a playground, and it pairs well with middle names of almost any length. Say it out loud with your last name and any middle names you're considering, and check the initials it makes.