Idamaria is a nun who specializes in demon exorcism and is romantically interested in Kucabara. It is later revealed that Idamaria is able to produce Dark Matter from her body. The source of the Dark Matter is said to be goddess of hell, Lilith.

Motoko Gettou is one of the protagonists of the series. Motoko's mother died when she was a young girl and she was adopted by three combat specialists. These "Three Fathers" trained her in karate, swordsmanship, submission techniques, close quarters combat and the handling of firearms. As a result of the excessive physical and mental strain placed on young Motoko during her training, she developed three split-personalities, collectively known as "HiFuMi". Together HiFuMi works to protect Motoko, though she sees HiFuMi as a burden to her and only wishes to live a normal life, but knows they are just trying to look after her safety. Initially shy, she warms up to Kouskegawa, though nervously states they are just friends every time someone suggests that they are a couple. Yet Motoko develops feelings for Kosukegawa as he does for her.

A high school senior and president of the school's kendo club, she is extremely skilled at close combat with a bokken. Calm and collected with a sense of pride in her skills, Saeko is among the most reliable of the group. Everyone can count on her combat skills to pull them through a crisis. Also throughout the journey, she begins to develop romantic feelings for Takashi. Not much is known about her family except for her father who had traveled abroad on a self-defense conference before the advent of the Outbreak. Saya's father, Souichirou Takagi, tells Saeko that her father once gave him guidance so to repay the favor, he gives her a very powerful sword, crafted in the Tokyo armory by General Murata during the Meiji Era.

A beautiful young woman in her mid-20's, Hae-Young teaches mathematics and also acts as the homeroom teacher for class 3-2, She lives with her sister and niece in an apartment block quite close to Jin-Ho. Her father’s unexpected departure from her life when she was young has had a huge impact on her. Even though she is extremely attractive and was apparently popular (and pursued) throughout her school life, she has become very guarded around men, feeling unable to trust or form relationships with them. Consequently she is still a virgin and even shares her first kiss with Jin-Ho during the course of the story.