Naozumi was known as a fierce warrior and, similar to his older brother, Magara Naotaka, Naozumi wielded a massive long sword (approximately 175 centimeters in length). It is not certain whether he used the sword in actual battle, but, while Ashikaga Yoshiaki was residing under the protection of the Asakura in Echizen, Naozumi showed him a massive sword that was 288 centimeters in length.
In the sixth month of 1570, at the Battle of Anegawa, Naozumi fought valiantly against the allied forces of the Oda and Tokugawa. Naozumi, Naotaka, and Naotaka’s son (Magara Takamoto), were all killed in action. The long sword used by Naozumi in Anegawa remains as a precious artifact at the Atsuta Shrine.
Naozumi’s older brother, Magara Naotaka, is referred to with the same common name of Jūrōzaemon, and, similar to Naozumi, wielded a massive long sword (approximately 175 centimeters in length), so there is a theory that the historical accounts relate to the same individual.