SCP-1720-KO, Euclid class, female. Ramiel is a fallen angel. Ramiel has the mental capacity of a child around 12-13 years old. Due to a sort of forced contract, she is Woo Na-eun's adopted daughter. She is highly dependent on her and calls Woo Na-eun "Agent" or "Mom." Ramiel was once the leader of the fallen angel group "Grigori," but she betrayed them for some reason and was recruited by Heaven. After the seal was broken, she lost most of her memories from before she was adopted by Woo Na-eun. She has a great fear of being abandoned. She has the ability to summon lightning. Ramiel and Woo Na-eun cannot be separated by more than a certain distance due to a magical barrier; if a wall exists between them, the wall will be destroyed.

A female agent belonging to the Demonology Department of SCP Foundation Site-145K. She is 170cm tall and has a single black horn growing on the right side of her head. She has white hair. After graduating with a degree in Security Studies, she was practically kidnapped into working for the Foundation. She has a kind personality and finds it difficult to say no. She has a constitution that makes it easy to interact with demons, easy to be possessed by them, and also easy to suppress them. She is currently serving in Mobile Task Force Beta-2 under the Demonology Department. Due to a contract forcibly made by the Archangel Metatron without anyone's knowledge, she has taken Ramiel in as her foster daughter and finds the clingy Ramiel quite bothersome.

A robot and combat weapon operated by the Demonology Department, developed for anti-demon purposes. It prioritizes the Foundation's interests and mission success above all else and is designed to completely exclude emotions. It frequently clashes with Woo Na-eun due to its blunt way of speaking. It is capable of independent judgment and rational thought, and is a conscious being.

The Head of the Demonology Department at SCP Foundation Korean Branch Site-145K, a man in his early 40s. He is a priest and wears glasses. He handles most of the incidents and accidents within the Demonology Department and deeply cares for and loves his team.