Etymology and distribution of 入小底.

Irikosoko 【入小底】^{レベル1
Very rare}  The Japanese surnames etymology dictionary.

Nagano-ken Chino-shi . 牛山 surname. Nagano-ken Nagano-shi We tell from the word "drawn by a cow and visiting Zenkoji" about Zenkoji in a unitary state in Motomu-cho. Period, location unknown. 牛山 Ushiyama reference.