This is a world where killing and torture are legalized. Sero, a part-time worker at a torture company, enjoys torturing people every day with his senior colleague, Siu. With the addition of new part-timers Mike and Hugh, fun torture life continues! The gap between the at-home, easy-going workplace and the gruesome torture is bound to attract a lot of addicts! (Source: Hakusensha, translated)

The king of Slantania has officially appointed Sei Takanashi as the Holy Saint—an omnipotent maiden summoned from another world to save the kingdom. After months of relentless fighting against monsters, Sei can finally relax and continue her study at the Medicinal Flora Research Institute. Although her relationship with Albert Hawke, the commander of the Third Order of Knights, gradually blossoms, her bachelorette status attracts unwanted attention from other men—much to Albert's dismay. Moreover, Tenyuu—one of the many princes from the faraway Zaidera Empire—has taken an interest in Slantania and its powerful healing potions. Given that Sei's identity is a national secret, she must lay low in the royal palace until Tenyuu satisfies his curiosity at the institute and returns to his country. Despite his unimpressive appearance, the foreign prince is far from clueless. He has come to Slantania for a clear reason, and Sei's unique skills may just hold the answer to his cryptic research.

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.

Not long after forming their partnership, detectives Ron Kamonohashi and Totomaru Isshiki have proven adept at solving various cases together. However, the two are further motivated to continue their work when they discover that the House of M—an infamous crime syndicate—orchestrated Ron's expulsion from the prestigious Detective Training Academy BLUE five years prior. It appears that this group is also linked to Ron's mysterious ability that causes those around him to lose their lives, a phenomenon which Ron is desperate to stop. A member of the House of M soon starts to commit boastful serial murders around Shibuya as an act of provocation toward Ron. Consequently, the investigative pair must do their best to apprehend the culprit for the sake of justice as well as learning more about Ron's dark past and present condition.