Fuwa Naomitsu served as a bushō during the Sengoku and Azuchi-Momoyama periods.  Naomitsu served as a retainer of the Saitō, the Oda, and the Maeda clans.  His common name was Hikosa.  Naomitsu was born as the son of Fuwa Mitsuharu, a retainer of the Saitō.  His formal wife was the daughter of Kitabatake Tomonori.

While serving Oda Nobunaga, Naomitsu and his father, Mitsuharu, participated in assorted battles.  Following the demise of Mitsuharu in Echizen Province around 1580, Naomitsu inherited the family and engaged in political affairs as one of the members of the Fuchū Group of Three.  After the death of Oda Nobunaga at the Honnō Temple Incident on 6/2 of 1582, Naomitsu aligned with Shibata Katsuie, serving under Sakuma Morimasa at the Battle of Shizugatake.  After losing in this battle, Naomitsu served Maeda Toshiie, and, at the Battle of Suemori Castle, joined the vanguard of the Maeda army in battle against the forces of Sassa Narimasa.