This individual was the son of an farming family during the peroid Miyamoto Musashi was alive, living an ordinary farm life and separated from common sense. That said, the man summoned in Sasaki Koujirou's place does come the closests to matching his parameters, so his personality would become Kojirou's personality and his monumental feats would become that of Kojirou rather than his own. The person summoned in his place is not a Heroic Spirit, but an existence closer to that of wraiths.
He did not actually exist, so it would be impossible to summon the Kojirou of legend as a Servant. Kojirou is known as a master swordsman whose existence is doubted even though his name remains recorded in history. In reality, the individual summoned as Sasaki Kojirou's True Name never had a true name.
Sasaki Kojirou is a mythical Japanese swordsman said to have faced Miyamoto Musashi in combat. 2.5.6 Event: CBC2023 Tales of Chaldean Heavy Industries ～B to B for Me and You～.2.5.5 Subspecies Singularity III: Shimosa.2.5.4 Summer Event: Chaldea Heat Odyssey.2.5.3 Summer Event: Chaldea Summer Memories.2.5.1 Do Moon Goddesses Dream of Dango?.
