- Born: 1565
- Died: 1582
- Other name: Nagasada
- Distinction: One of the Vassals of Oda Nobunaga
- Japanese: 森蘭丸 (Mori Ranmaru)
Ranmaru was the third son of Mori Yoshinari and was born at Kanayama castle in Mino. In his youth he became a favored page of Oda Nobunaga, who was impressed by the boy's bearing and intelligence. While named the lord of Iwamura castle in Mino in 1582, he was at the side of Oda Nobunaga when the latter was attacked by Akechi troops at Honnoji in June 1582. Nagasada is thought to have assisted Nobunaga in committing suicide before perishing, though this is impossible to know for certain. Two of Nagasada's younger brothers, Nagataka and Nagauji, were also Nobunaga's pages and died at Honnoji as well.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005