Ron Kamonohashi, the best student in the history of the elite Detective Training Academy BLUE, has been living as a recluse since BLUE expelled him five years ago. Moreover, he is forbidden to work as a detective, having barely escaped execution after getting involved in a murder case while he was still attending the school. Ron's situation changes drastically when police detective Totomaru Isshiki, following the advice of a senior colleague, seeks him out for help with a criminal case that has remained unsolved for months. Ron reluctantly agrees to help Totomaru and uses his phenomenal intuition to discover the culprit in less than a day. However, it appears that Ron suffers from a mysterious condition that can cause those around him to lose their lives. To Ron's great surprise, Totomaru manages to save the life of someone whom Ron put in jeopardy. As the unlikely duo starts solving crimes one after another, BLUE sends operatives after its former student to find out if he has resumed investigative work. Fighting against murderers, rogue detectives, and the Metropolitan Police Department, Ron and Totomaru must join forces if they want to survive and see justice prevail.

As the commander of the Imperial Army's Third Legion, the Royal Empire's princess has led humanity to countless victories against the demonic Hellhorde. However, she has now been captured by the enemy and confined to the dungeons, with her sentient sword, Ex, as her only company. Due to her royal status, the princess knows invaluable secrets that would help the Hellhorde achieve dominance. To have her reveal all the information they need, the demons do not hesitate to subject the princess to the most vile forms of torture—that is, tempting her with delicious food, lasting friendships, adorable animals, and the most enjoyable experiences imaginable.

Spirits have always been attracted to Keitarou Gentouga due to his strong spiritual presence. A traumatic encounter with one had caused his right hand to be cursed, forcing him to wear a glove at all times. Now a college freshman, Keitarou is trying to live as normal a life as possible. With the encouragement of his childhood friend Eiko Houzuki, he becomes a private tutor. Since he is at the top of his intake class, his first client is the tutoring firm's most promising student, Yayoi Houzuki. To Keitarou's surprise, Yayoi is Eiko's cousin, and she possesses two pupils in each eye—allowing her to see into the spirit world and purposely seek vengeful spirits to exorcise. Ever since a car accident killed both her parents, Yayoi has been searching for the powerful spirit that kidnapped her mother's departed soul. Seeing that spirits are so attracted to Keitarou, she ropes him into helping her collect other evil spirits that will assist in her future fight. Although her quest is dangerous, Keitarou reluctantly decides to join her, even as each new spirit they meet has him questioning his resolve at every turn.

In a small church atop a hill, Pastor Lawrence looks after Saint Cecilia. Her presence is a beacon of hope for the villagers, as her mysterious powers protect them from the weakness of their minds and outside evils. While she appears dignified in front of the villagers, Cecilia allows her lazy side to show when alone with the pastor. Although Cecilia is the guardian of the people, Lawrence is determined to shield her from harm. Unbeknownst to Lawrence, Cecilia harbors a huge crush on him. She accompanies him on his shopping trips and provides him with divine protection every day. Despite Lawrence remaining oblivious to her true feelings, Cecilia continues to shower him with obvious displays of affection as the bond between them grows.