Personification of the tachi ''Usu-midori'', treasure of the Minamoto Clan. The name used for Touken Ranbu is one of many that the sword had obtained over the years, ''Hizamaru'' in particular referencing a practice test where the sword cut through the knees of an opponent.
The game portrays him as the younger brother/ younger brother figure of fellow Minamoto clan sword Higekiri, and is highly affectionate towards him though the historical Higekiri was used to cut Usu-midori (thus earning the name ''Tomokiri'', "Friend Cutter"). This is because of the relationship between their owners; Hizamaru's owner Minamoto no Yoshitsune had his brother Yoritomo, owner of Higekiri, in high regard. He also frets about becoming "separated" from his brother again, as seen in his citadel, pre-battle quote and sword breaking dialogue.
