Nagai Naoyuki (?? ??, December 21, 1816 – July 1, 1896), also known as Nagai Genba (?? ??) or Nagai Mondonosho (?? ???), was a Japanese hatamoto under the Tokugawa of Bakumatsu period Japan.
His great-great-grandchild was Yukio Mishima.
Naoyuki's adopted son, Iwanojo Nagai, was the father of Natsu, who was Mishima's grandmother.
Iwanojo's real father was Nagasumi Miyoshi (Miyoshi clan) who was a Tokugawa retainer.