Search gender: all male female ユイコウ Japanese Boy Names Variations. 1 names found. gender: all male female Name: yuiko Katakana: ユイコウ 0 Kanji: 唯恒 Meaning: 唯That's it. Just one. Only. A word expressing limitation or emphasis. Reply. A reply of acceptance that is answered immediately. 恒Always. Always the same, constant. Unchanging. Continuously. Long time. Permanently. You can save your favorite names with NAZUKE PON > About Japanese Names > Search Japanese Names By Kanji > ユイコウ Japanese Boy Names Variations.