Keiji's real name historically is Toshimasu ironically. The name Keiji comes from Edo legends, which mean "lead cautiously" due to his reckless personality. A lot of Keiji's visual design is inspired by his characters in the comic Hana no Keiji. His line during his Musou "Why do you think tigers are strong? Because they were born that way!" is a quote from the comic. His alternate outfit is also a reference to an event in the comic where Keiji shaves his head as a peace messenger to Ieyasu.

Many of Keij's weapons and fighting style are also inspired by kabukimono as he celebrates and dances during battle.