Seiji is a distinctive boys' name in United States, ranking #6855 in 2001 with 10 recorded births. This places Seiji in the bottom 44% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2007 with 19 births ranking #4951. Since 1996, the popularity has increased by 25.0%. In 2001, approximately 1 in every 194,283 boys born was named Seiji. FALLING Recent data shows the name is currently falling.