Shinsuke buys a yoto sword (mysterious sword) named Muramasa at a gadget shop he happened to visit by chance, and immediately when holding the sword, he becomes deranged and starts running to kill Omiyo.
たまたま来た小道具屋から妖刀村正を買った新助は、刀を手にした途端、狂い出しておみよを殺しに駆け出していく。