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.

Twenty-seven-year-old salarywoman Midori Akitsu suddenly dies in her apartment due to overwork. As her spirit leaves her body, God appears before her, offering Midori a second chance at life in another world called Asdyllon. There, she must observe how badly humans persecute other species and judge if they should continue existing. To help her get started, God grants Midori a special ability: to be liked by all kinds of non-humans—whether it be animals or holy beasts—enabling her to embrace and cuddle them as much as she wants. Now reborn as Nefertima Osfe, a duke's daughter, she enjoys her new life to the fullest alongside her adorable companions. However, it will not be long before she discovers what her task truly entails and that her time in this world will not always be fluffy.

In her first life, the renowned and genius surgeon Dr. Aoi Takamoto was Elise de Clorance, a villainess of noble descent. Elise's selfishness, insolence, and obsessive love for her fiancé—Prince Linden de Romanoff—led to the deaths of her family members and, eventually, herself. Only after being reborn did Elise realize the error of her ways and decide that, instead of ruining lives, she would devote herself to saving them. But a tragic airplane crash robs her of her dreams too soon. By a miracle, Elise wakes up in her original body before her official engagement to Linden. Recognizing the chance to cherish her loving family and free Linden from an unwanted marriage, Elise wishes to use her advanced medical knowledge to continue down the path of saving lives. In a deal with the emperor, Elise is given only six months to prove that her true place is not on the throne, but rather with the wounded and ailing who desperately need her help.