Following the revelations of the archangel Gabriel, Ente Isla hero Emilia Justina—who lives on Earth under the alias Emi Yusa—starts doubting the validity of her mission to slay the Demon Lord Satan, now reduced to a modest employee of MgRonald's as Sadao Maou. At the same time, Sadao's high school-aged coworker Chiho Sasaki pursues a new dream with hopes to protect not only herself but also her friends. Secretly training with Emi and Suzuno Kamazuki to develop telepathic powers, Chiho's training is cut short when a group of demons abducts her. As angel and demon attacks threaten the fragile peace between the two worlds, Sadao and Emi need to put their troubled past behind them if they want to have a chance to find their new purpose in life.

Due to poor finances, an epidemic, and famine, the once prosperous Tearmoon Empire ultimately falls to a revolution instigated by its citizens and supported by neighboring nations. The rebellion also brings dire consequences for Mia Luna Tearmoon, the empire's extremely spoiled princess, who endures three years in the dungeons before facing execution. By some miracle, Mia finds herself reincarnated as her 12-year-old self, retaining full memories of everything that had transpired. With the pain of the guillotine blade freshly imprinted on her neck, Mia is determined to use this second chance at life to avoid the grim fate that awaits her. She utilizes all her knowledge to improve the state of the kingdom and gather personal allies, inadvertently winning over the people's hearts and becoming beloved as a saint.

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.

Since childhood, 15-year-old Umika Konohoshi has been fascinated by aliens, hoping to one day voyage to outer space and befriend them. Unfortunately, this fixation has caused her peers to label her as odd, intensifying her struggle with severe social anxiety. Nevertheless, Umika's passion for the extraterrestrial persists, and she deeply believes that her true purpose is outside the confines of Earth. On her first day of high school, Umika's wish of meeting an alien seems to have finally come true when she encounters Yuu Akeuchi—a classmate who claims to have crash-landed on Earth with no recollections of her past. Umika tries to seize this opportunity to make friends with Yuu, but her lack of confidence hinders her. Sensing Umika's distress, Yuu suddenly uses a strange power to delve deep into her mind, thus sparking a friendship that may just help Umika reach her dreams.