Kaisei
Meaningoften clear weather · Japanese
Kaisei is a Japanese boy name often meaning “clear weather”. 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 simple to spell and say, and it pairs well with middle names of almost any length.
Did you know?
- Hidden namesLook closely: Kaisei has the name Kai hiding inside it.
- GenerationKaisei peaked in 2007, which makes it a Gen Z name. The typical Kaisei you'd meet today is about 18 years old.
- Roll callIn a typical school of 500 kids, your Kaisei would very likely be the only one. About 1 in 285,714 baby boys got the name in 2025.
- HistoryKaisei first shows up in US birth records in 2005, the first year at least 5 babies got it. That makes it a fairly new name, younger than many of today's parents.
US births per million boys, 2005–2025
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Popularity: U.S. Social Security Administration (babies with 5+ births per year).
About the name Kaisei
Kaisei is a boy name of Japanese origin meaning “often clear weather”. Its two syllables give it an easy rhythm, and the open vowel at the end makes it sound soft and warm. It's a fresh, modern name that only arrived in US birth records in recent decades. It's rarely heard today, so it stands out while still being a real, established name.
Origin:Japanese names
Other spellings of Kaisei
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 Kaisei
What does the name Kaisei mean?
Kaisei means “often clear weather” and comes from Japanese.
What is the origin of the name Kaisei?
Kaisei is Japanese in origin. Other Japanese names to consider are Asa (“healer”), Rio (“river”), Akari (“light, brightness”) and Kenzo (“often healthy third son”).
Is Kaisei a boy or girl name?
Kaisei is a boy name. In 2025, 6 US boys were named Kaisei.
How popular is the name Kaisei?
Kaisei ranked #10,695 for US boys in 2025, given to 6 babies. Its best year was 2007, when it reached #7,590.
What names are similar to Kaisei?
If you like Kaisei, you might also like Caysey and Kaysey. Caysey is another spelling of the same name.
What should I know before naming my baby Kaisei?
Kaisei is a Japanese boy name often meaning “clear weather”. 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 simple to spell and say, 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.