- Birth: 1830
- Death: 1895
- Other Names: 山口泉処 (Yamaguchi Sensho)
- Titles: Tsukaiban, Metsuke, Gaikoku Bugyô, Edo Machi Bugyô
- Japanese: 山口 直毅 (Yamaguchi Naoki)
Yamaguchi Naoki was initially a Confucian scholar who was appointed as a Tsukaiban in 1860, and promoted to Metsuke by the end of the same year. In 1863, he accompanied Tokugawa Iemochi on his historic trip to Kyoto (along with the Shinsengumi). During the same year, he was appointed administrator of Kanagawa.
- Beerens, Anna. Interview with a Bakumatsu Official: A Translation from Kyuji Shimonroku Monumenta Nipponica, Vol. 55, No. 3. (Autumn, 2000), pp. 369-398.