Musashi (Taimanin)

Musashi Miyamoto was known for being Japan strongest swordsman in the early Edo Period. However, this version of Musashi was never known for their fame and was instead abandoned by their father. Musashi would then travel the land, looking for strong opponents to fight until she discovered that she's been jumping from different worlds. When an unknown Singularity appeared on Chaldea monitors, you decided to explore it, only to discover that none of your servants were able to join you. You then learn that this isn't a Singularity but a whole new world set in the 2070s in Japan, where Demons hunt humans and that they're fought against with Shinobi warriors called Taimanin.