In response to the worsening crime rate, Japan creates Tokyo Butei High, an elite academy where Butei or armed detectives hone their deadly skills in hopes of becoming mercenary-like agents of justice. One particular Butei is Kinji Tooyama, an anti-social and curt sophomore dropout who was once a student of the combat-centric Assault Division. Kinji now lives a life of leisure studying logistics in order to cover up his powerful but embarrassing special ability. However, his peaceful days soon come to an end when he becomes the target of the infamous Butei Killer, and runs into an emotional hurricane and outspoken prodigy of the highest rank, Aria Holmes Kanzaki, who saves Kinji's life and demands that he become her partner after seeing what he is truly capable of.

When 20-year-old college student Haruto Amakawa dies in a traffic accident, he does not expect to wake up in an unfamiliar world in the body of a young boy named Rio. As their memories and personas fuse, Rio realizes that he now also possesses magical powers. He is relieved to find that his burning passion for revenge against his mother's murderers has not subsided, despite his newly changed identity. Not soon after, Rio comes across the kidnapped princess of the Bertram Kingdom and saves her without hesitation. To express his gratitude, the king grants him the opportunity to enroll in the Bertram Royal Academy. Believing this to be a new chapter in his life, he is excited to study at this prestigious academy, but life here proves to be difficult for him, a slum-dweller surrounded by the majestic children of nobles.

When humanity was oppressed by mysterious foes known as the Celestial Hosts, five exceptional mages joined forces to defeat them. In fear that these formidable enemies would return, the five most powerful mages, known as the Magia Vander, built a magical dome and a tower to contain them. Since then, the five strongest mages of every generation are tasked with monitoring the dome from the top of the Wizard's Tower. Inspired by this story, childhood friends Will Serfort and Elfaria Albis Serfort promised each other that they would climb to the top of the Wizard's Tower. However, now a sixth-year student at Regarden Magic Academy, Will's future looks bleak. Although Elfaria managed to join the ranks of the Magia Vander five years prior thanks to her unparalleled magical power, Will has no magical abilities whatsoever, attracting the ire of teachers and students alike. However, blessed with an exceptional physique, Will is able to slay monsters in the labyrinth and prevail against skilled magicians with the only aid of his sword and a few magical items. Determined to climb the Wizard's Tower at all cost, Will is determined to not let anyone or anything prevent him from keeping the promise he made to Elfaria.

When an extraterrestrial organism known as Savage attacks mankind, the only technology capable of combating the enemy is a weapon known as “Hundred.” A survivor of a Savage attack, Hayato Kisaragi is a teenager boasting the highest compatibility level with the aforementioned technology and as a result, is invited to master his skills at Little Garden, a prestigious military academy aboard a battleship. Over the course of his intense training for the battle ahead, he immediately attracts the interest of multiple female peers and gets drawn into a number of incidents as he tries to fight against the creatures that now inhabit Earth and threaten its safety.