Solitär is a demon who conducts research on living creatures, including humans, and an acquaintance of Macht, sharing an interest in humankind. Beneath her nonchalant attitude, however, lies an extremely dangerous demon, comparable to the members of the Seven Sages of Destruction.

"If you ever encounter a nameless Great Demon, flee without hesitation. Every single Great Demon that possesses vast mana, without exception, has lived for eons. However, if there is still no such record of them amongst mankind, there is a strong possibility that everyone who encountered them was massacred." -Frieren