Etymology and distribution of 後門.

Ushirokado 【後門】^{レベル2
About 10}  The Japanese surnames etymology dictionary.

Saga-ken , Nagasaki-ken , Hyougo-ken . Originated from Ureshino -shi of Saga-ken Ureshino -shi . In the Northern and Morning era, the name of a place with a record in the notation "Utsushino". The surname was also written as "Utsushino". It is unknown whether Utsunoshino will exist.