The Prismriver Sisters are a phantom ensemble that performs concerts at events such as youkai parties. They have the ability to play musical instruments without using hands. The eldest sister Lunasa plays the violin, the second sister Merlin plays the trumpet, and the third sister Lyrica plays the keyboard.

The Prismriver sisters are poltergeists. Lunasa is the leader of the ensemble, Merlin is the most popular, and Lyrica can perform on any instrument. The ensemble is so popular in Gensokyo that each performer has their own fans.

There are many theories about poltergeists. Those knowledgeable of them agree that while poltergeists are similar to phantoms, they are not exactly the same. It is still a hotly debated topic with new views emerging constantly.

It is said that the Prismriver sisters once lived as humans. When they were still alive, there were actually four sisters in total, including the youngest.

"Your foundation is the human who created you, but that human is gone," said the Yama, judge of the deceased, to the Prismriver Sisters. When the human who created the three poltergeist sisters disappeared, the three sisters should have disappeared as well, but for some reason, they didn't. They still remain in Gensokyo.