Kaisei is a very rare variant of Kasey that peaked in 2007 and remains in steady use.
Kaisei is a boy name. In 2025 it ranked #11,319 for boy births in the United States (and #23,334 across all names), given to 6 babies. Kaisei first appears in 2005 and peaked in 2007 (10 births).
| Year | U.S. births | U.S. + territories | Rank |
|---|---|---|---|
| 2025 | 6 | 6 | #11,319 |
| 2024 | 9 | 9 | #8,658 |
| 2023 | 6 | 6 | #11,518 |
| 2022 | 7 | 7 | #10,322 |
| 2021 | 6 | 6 | #11,432 |
| 2019 | 9 | 9 | #8,520 |
| 2018 | 5 | 5 | #13,143 |
| 2017 | 9 | 9 | #8,494 |
| 2016 | 6 | 6 | #11,423 |
| 2015 | 7 | 7 | #10,073 |
| 2014 | 9 | 9 | #8,465 |
| 2013 | 9 | 9 | #8,447 |
| 2012 | 7 | 7 | #10,250 |
| 2010 | 9 | 9 | #8,451 |
| 2009 | 7 | 7 | #10,422 |
| 2008 | 5 | 5 | #13,565 |
| 2007 | 10 | 10 | #7,881 |
| 2006 | 6 | 6 | #11,339 |
| 2005 | 5 | 5 | #12,367 |