Meaning A boy's name of Japanese origin, it means "correct first-born son". Origin of Seiichi Japanese +-100%Zoom level changed to 1 Popular Middle Names Pronunciation 🔊 Listen Seiichi Similar Names Seiji Masaaki Masao Masahiko Masaki Masashi Masayuki Tadashi Shinji Shuichi Year by Year Popularity of Seiichi