It is an anime depicting interaction between humans and youkai. Besides the conversation between high school students, conversations with youkai who speaks in a bit old-fashioned way also appear.
It is a story of human-shaped jewels. The fact that the jewels do not have sex is a point when learning Japanese. Many characters talks in the boy’s tone, however, there are characters who talk in the girl’s tone, such as the diamond.
The main characters use common Japanese in this work. They use a frank and polite way of speaking depending on the scene. Words related to youkai are unique, but slang words do not come out.