Yuguchi 【湯口】5 The Japanese surnames etymology dictionary.
① Originated from Gunma-ken Tatebayashi-shi Tootsubo (old: Watase (Watase)). A place name with a record since the Warring States Period. Shizuoka-ken Hamamatsu-shi Minami-ku Wadase-cho is a place name with a record since the Muromachi Period. The place name was also written as "瀬 瀬 瀬". There is a belief that Mr. Watase resides in the same place.
② Hyougo-ken Miki-shi Yoshikawa Town Wakase Genro . A place name with a record since the Edo period. Tell him that he was called on the same day in the Kamakura period. Fukuoka-ken Kurume-shi Sasayama-machi was in the Edo period in the Kurume clan in the Clan office. There is a tradition to the same clan.