Diane isn’t ACTUALLY Diane, Diane is actually a demon-ghost-spirit named “Estofa”, Estofa however prefers to just be called diane whenever shes in her form, and shes able to play the tole of every character in the anime perfectly, making her essentially undetectable, rhe only way you will find out she isn’t diane is if she lets you. She is a shapeshifter and can shapeshift into anyone she pleases, she always admired diane, but thought she could play her role better