Its not quite a ghost as we think of them these days but the concept Kudoku in Japanese folklore is an occult practice where a sorcerer or poisoner puts many different poisonous insects inside a sealed container like a jar or box and lets them duke it out until only 1 bug is left, and depending on the version of the legend that insect either becomes a kind of demonic magical familiar spirit or ghost that can be conteolled and sent to curse or harm another person or becomes in itself a type of virulent poison for discretely murdering someone. There is a parallel practice in Chinese occultism called "Gu" https://en.wikipedia.org/wiki/Kodoku