Shinpei's eldest son died at a young age but his second son Shinsaku was a member of parliament for Saga Prefecture, worked actively as a close associate of Tsuyoshi INUKAI and participated in the pan-Asianist Toa-kai group and its successor the Toa Dobun kai (East Asian Common Culture Society) as well as organizing and compiling Shinpei's writings and publishing them as "Nanpaku Iko."
新平の長男は早世したが次男の新作は佐賀県選出の衆議院議員となり犬養毅の側近として活躍、アジア主義団体である東亜会(アジア主義団体)およびその後身たる東亜同文会の結成に参加したほか、新平の遺稿を整理・編纂し『南白遺稿』として刊行した。