Shirou, Rin, and Sakura find themselves stranded in another world courtesy of a certain Wizard. To survive, the trio starts a clinic while they get their bearings on this alien world. Unfortunately for them, they chose the best (or worst) possible disease to treat. "Shirou, what is that?" "Tainted Mana Crystals."
Shirou dies, and the corrupted grail in his soul grants an incomplete wish, reincarnating Shirou's soul. An old soul meets a new world, tragedy strikes, the sleeping UBW awakens, and memories resurface. Shirou embarks on an adventure, seeking what he has lost.