Kaguya Houraisan (蓬莱山 輝夜 Houraisan Kaguya) is an immortal Lunarian who was once a princess of Lunar Capital on the Moon, before fleeing and residing in Eientei alongside Eirin Yagokoro. She first appears as the true Stage 6 boss of Imperishable Night, and subsequently appears in many print works, including prominently in Touhou Bougetsushou.