Etymology and distribution of 天坊.

Tenbou 【天坊】^{レベル2
About 30}  The Japanese surnames etymology dictionary.

Kagoshima-ken Isa-shi . The literal meaning is "both ends of the bow", "a part with a notch at the end of the arrow". Kagoshima-ken Isa-shi Distributed in Oguchi Tashiro. There is a 筈山 last name in the same 筈山 . 筈山 Hazuyama reference.