Search gender: all male female Gengai Boy Name Meaning, Kanji Variations. 1 names found. gender: all male female Name: gengai Katakana: ゲンガイ 0 Kanji: 源外 Meaning: 源Source. The source from which the water of a river flows. The beginning of something happening. 外Outside You can save your favorite names with NAZUKE PON > About Japanese Names > Search For Japanese Names > Gengai Boy Name Meaning, Kanji Variations.