Search gender: all male female コウサイ Japanese Boy Names Variations. 21 names found. gender: all male female Name: kosai Katakana: コウサイ 0 Kanji: 虹彩 Meaning: 虹Rainbow. 彩To color. Add color. A combination of various colors. To make up. Pattern. Luster. Brilliance. Appearance. Figure. You can save your favorite names with prev12 NAZUKE PON > About Japanese Names > Search Japanese Names By Kanji > コウサイ Japanese Boy Names Variations.