Seiji is a distinctive boys' name in United States, ranking #8804 in 2023 with 9 recorded births. The name reached its all-time peak in 2007 with 19 births ranking #4951. Since 1996, the popularity has increased by 12.5%. In 2023, approximately 1 in every 189,839 boys born was named Seiji. FALLING Recent data shows the name is currently falling.