Search gender: all male female セイオ Japanese Boy Names Variations. 1 names found. gender: all male female Name: seio Katakana: セイオ 0 Kanji: 誠夫 Meaning: 誠True. A heart without lies and falsehoods. Sincerity. Truly. 夫Husband. A man who is married. An adult male. A full-fledged man. A respectable man. A man engaged in labor. You can save your favorite names with NAZUKE PON > About Japanese Names > Search Japanese Names By Kanji > セイオ Japanese Boy Names Variations.