The Eight String Harp, Part 1 Episode 9

A monk dies because of playing an eight-stringed koto, but his soul still dwells within the instrument and plays it. Meanwhile, an Oni places a sleeping curse on Akane through the vengeful spirit, forcing the Hachiyo to go and look at the monk's cursed eight-stringed koto and remove the additional string that was added to it to break the demon's curse. The Oni who created the kin was captured.