After the demise of the demon king, the resulting power vacuum has broken the balance of the world. Eager to claim this power for themselves, self-proclaimed demon kings from various worlds assemble in the New Principality of Lithia to fight for it. Among them, master swordsman Soujirou Yagyuu seeks to take this coveted position for himself. Joined by Tooi Kagizume no Yuno, a young girl he saved from an army of golems that destroyed her city, Soujirou enters Lithia to battle his way to the title. At the same time, the leaders of the Aureatia Kingdom seek to destabilize Lithia by launching bandits after the convoys of merchandise transiting through the principality. Enraged, Imashime of Taren, the founder of Lithia and defector from Aureatia, sends vicious thief Kasasagi no Dakai to investigate the origin of these attacks. With war on the brink of eruption, no one can predict what influence the contenders for the demon king's throne will have on the coming conflict.

After escaping a violent encounter, Touko finds herself lost in the chaos of a city under invasion by Spiders, a tribe of people with dangerous supernatural abilities. Touko has traveled to the city intending to return the possessions of Haijuu, a fire hunter who died protecting her. She is aided by Haijuu's dog, Kanata, and Akira, a fire hunter who has protected her on her journey so far. When Akira is drawn away by an important task, Touko is swept into the battle's confusion to begin a new journey of her own. Meanwhile, Haijuu's son Koushi fights to defend the city. Though physically unremarkable, Koushi's ingenuity has aided in the development of a few useful weapons. These include a powerful cannon capable of casting down ungodly lightning to smite the invading forces. With such destructive force seen as an offense to the gods, the deity Hibari seeks to stop him. As they are both drawn into the unraveling plans of scheming gods and humans alike, Touko and Koushi struggle to survive.

While exploring a labyrinth, Rentt Faina, an adventurer with lots of experience but little to show for it, is killed by a dragon upon discovering its lair. Shockingly, he wakes up to find himself turned into a skeleton, the lowest class of undead monsters. As Rentt fights against the other monsters of the labyrinth, he discovers that slaying them gains him experience towards higher stages of undead evolution—even ones with flesh! With this revelation in hand, Rentt obtains a new objective in his undeath: keep evolving in the hope of eventually becoming a vampire, the highest form of undead that is nearly indistinguishable from human beings. Despite being forced to hide his past identity and monstrous nature under an unremovable mask, Rentt manages to return to a semblance of his former life. Granted shelter by Lorraine Vivier, an elite researcher and retired adventurer, Rentt assumes her surname and starts over from scratch as a rookie. Determined to pursue his childhood dream and become a mithril-class adventurer, Rentt must be cautious not to disclose his new bodily circumstances, lest the adventurers’ guild seek to exterminate the monster he has become.

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.