In his past life, Prince Lloyd de Saloum was a commoner who could not become adept at magic, no matter how knowledgeable or obsessed he was about it. Now reincarnated into his current royal lineage, he receives a body with seemingly endless mana, making his desire to master all things arcane attainable. Moreover, as the seventh prince of the kingdom, Lloyd has no claim to the throne, allowing him to nurture his abilities as freely as he wants. Unfortunately for Lloyd, ancient seals that imprison powerful demons begin to break down and release the horrors within, endangering the peace. With these monstrosities roaming around, Lloyd's overwhelming magical prowess is the ultimate weapon that can neutralize these threats before all things descend to chaos.

Prince Lloyd de Saloum—once a commoner who could never grasp magic—is now blessed with inexhaustible mana and has all the time in the world to master it, as he has no claim to the throne. After mastering demonic magic, he sets his sights on the Church to learn the secrets of divine magic that will bring him one step closer to completing his arsenal. However, due to his fondness for unholy magic, he draws the scrutiny of divine beings who see him as little more than a demonic spawn.

Shizuma Origasa, once a renowned samurai in the Aizu Domain, has fallen on hard times following his home region's crushing defeat against the new imperial government. To make ends meet, Shizuma now works as a rickshaw puller in Tokyo. Meanwhile, he tirelessly searches for his missing fiancée, Sumie Kanomata, the younger sister of his close friend Gennosuke, who had entrusted Shizuma with her safety in his final moments. After foiling an assassination plot, Shizuma is hired by the police force, and he uses this opportunity to further his pursuit of Sumie. However, he soon lands in a whirlpool of political conspiracies involving government loyalists, persistent rebels, cunning courtesans, meddlesome foreigners, and even a mysterious yakuza member, Kyoushirou Shuragami.