Mori Ranmaru (森蘭丸, Mori Ranmaru?)(1565–June 21, 1582), born Mori Nagasada (森長定), was the son of Mori Yoshinari, and the younger brother of Mori Nagayoshi, from the province of Mino. From an early age, Ranmaru was an attendant to Oda Nobunaga. Recognized for his talent and loyalty, he was appointed to a responsible post. At Ōmi, he was given 500 koku, and after Takeda Katsuyori's death, he was awarded the 50,000 koku at Iwamura Castle. Ranmaru and his younger brothers perished defending Oda Nobunaga during the Incident at Honnō-ji. Ranmaru Mori committed seppuku with Nobunaga. Oda and Mori's lord-vassal relationship followed the shudo tradition, and was widely admired in Japan for its strength. In fictional works featuring him, Ranmaru is often depicted as having an extremely feminine appearance.