Among the descendants of the Kawaguchi Family remains a story that since Ryojiro was given an important position such as Hisamitsu's shosei (a post managing clerical works) although he was just a so-called 'Shimagoro' (countryman from island) from Tanega-shima Island, some people were jealous of him and put a crime upon him.
川口家の子孫の間には、種子島出身のいわゆる「島五郎（しまごろ）」であるのに久光の書生として重用されたことを周囲に嫉まれて罪を着せられたという言い伝えもある。