Senji Muramasa is a Saber-class Pseudo-Servant in Fate/Grand Order, embodying the spirit of the legendary Japanese swordsmith Muramasa within Shirou Emiya's body. He wields powerful demonic swords such as Tsumugari Muramasa and Myoujingiri Muramasa, capable of cutting gods and demons. As a wandering spirit unsure of his vessel's persona, he relies heavily on his Noble Phantasm for high damage in battles, with strong critical hits supported by team setups. He appears in the game's story and manga adaptation by Wataru Rei.