Hizamaru was a sword which MINAMOTO no Mitsunaka had made during the Heian period, handed down as a sword of successive generations of Genji, together with Higekiri. The blade length is about 81 cm.
According to Tsurugi no maki (chapter titled "Tsurugi" or sword) of Heike Monogatari (The tale of the Heike), the sword craftsman was "a craftsman of iron facon from Tang who lived in Deyama, Mikasa no Kori, Chikuzen Province," however, the details are unknown. Hizamaru was named after an event that occurred when trying it out on a criminal, it cut through to the criminal's knees.
In the generation of MINAMOTO no Yorimitsu, Hizamaru was renamed Kumokiri as he cut Tsuchigumo (a spider) that made him suffer from a fever. After that, the sword was renamed again and again. In the generation of MINAMOTO no Tameyoshi, the sword was renamed Hoemaru as it sounded like snakes crying during the night. After that, the sword was handed over to Kyoshin, steward, KUMANO, MINAMOTO no Tameyoshi's son-in-law; however, he thought that; "I should not own a sword of successive generations of Genji" and thus handed it over to Gongen who had the mother of Genji. After that, Gongen handed it over to MINAMOTO no Yoshitsune, who was very pleased with it and renamed it Usumidori. The name Usumidori originates from the mountains of Kumano in spring.
After Yoshitsune was defeated, Usumidori (or Hizamaru) was handed over to his older brother MINAMOTO no Yoritomo, by which ironically the two swords Hizamaru and Higekiri (made by the same person) got together again.
Note: the description of Hizamaru appears in Tsurugi no maki of Heike Monogatari. It is generally considered that the descriptions in Tsurugi no maki should not be regarded as historical facts; therefore, the description of Hizamaru should not be regarded as historical fact.