Etymology and distribution of 河之口.

Gonokuchi 【河之口】^{レベル3
About 50}  The Japanese surnames etymology dictionary.

Fukuoka-ken Noogata-shi . Thing . From the tongue. Fukuoka-ken Noogata-shi The upper boundary is based. Mr. Utsunomiya who was a vice president of Mr. Otomo in Ooita-ken (formerly Bungo country) in the same place tells that it was given in the meaning "to rule rationally with bastards" because his poor tongue was Muromachi period. 宇都宮 Utsunomiya reference.

※ Ehime-ken Yawatahama-shi The tongue between the tongues is a place name with a record since the Muromachi era.