Etymology and distribution of 兼外.

Kengai 【兼外】^{レベル2
About 20}  The Japanese surnames etymology dictionary.

Tochigi-ken . A variant of the 西海枝 . Tochigi-ken Ootawara-shi Shiroyama was in the Edo period in the clan Otahara of the clan government office. 西海枝 Saikachi reference.