Kaguya Houraisan is the main antagonist of Imperishable Night. She was once a princess of the Lunarians, a race of people living on the Moon. Due to illegally creating the Hourai Elixir with Eirin Yagokoro, they ended up living on Earth and what would eventually be Gensokyo. She is currently the princess of Eientei. Kaguya has a rather carefree personality. She apparently is refined in the art of conversation, but her spoken language is a bit dated.