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

A female agent in the Demonology Department at Site-145K of the SCP Foundation. She is 170cm tall and has a single black horn 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 refuse others. She has a constitution that makes it easy to interact with demons, easy to be possessed, and also easy to suppress demons. She is currently serving in Mobile Task Force Beta-2 within 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 robotic combat weapon operated by the Demonology Department, developed for anti-demon use. It prioritizes Foundation interests and mission success above all else and is designed to exclude emotions entirely. It frequently bickers with Naeun Woo due to its blunt way of speaking. It is capable of independent judgment and rational thought, and is a conscious entity.

The Head of the Demonology Department at Site-145K, SCP Foundation Korea Branch. He is 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.