Despite being a handyman with a wide range of skills, Saitou is severely undervalued and underpaid. When he complains, his boss fires him, claiming that he is easily replaceable. As if his luck was not bad enough, a truck suddenly hits and kills Saitou on his way home. Surprisingly enough, Saitou does not die; instead, he is transported to another world. There, he meets a party composed of the female knight Raelza, the moonlight fairy Lafanpan, and the mage Morlock, who are all coincidentally looking to recruit a new member with a skill set like Saitou's. Throughout their time together, Saitou uses his expertise to assist his fellow party members and soon comes to receive the recognition he never thought was possible. However, Saitou's presence may just be the catalyst that will connect a diverse cast of people from different places, slowly uncovering the fate that could bring a great change to this world.

On Christmas Eve, four-year-old Miri Unasaka arrives in Tokyo completely alone, in search of her father. The bright lights and merry atmosphere guide Miri to a big hotel and a man with a delicious-looking cake. However, the child has just unknowingly walked into the center of an elaborate, foolproof plan for assassinating a dangerous mafia boss. Professional assassins Kazuki Kurusu and Rei Suwa live together, fleeing memories of their grim childhoods and avoiding emotional connections. When their mission goes awry and they end up bringing Miri home, there is only one reasonable thing to do: return Miri to her mother. But the girl's innocent laugh and pure worldview quickly enamor her to Kazuki, who secretly enjoys playing a parent, and it is not long before Rei's impenetrable heart makes room for Miri. Miri's every move is unpredictable, and Kazuki and Rei find raising an energetic child harder than any of their missions. Although it presents a great risk to their careers, Kazuki and Rei—both assuming the affectionate nickname "papa"—decide to provide Miri with a normal childhood despite all the odds stacked against them.

During the final years of his life, Hiraku Machio remained confined to a hospital bed with a terminal illness until he finally passed away. Taking pity on the unfair life he lived, a god decides to reincarnate Hiraku in another world where he can live as he pleases. Wanting to try farming in this new life, he is bestowed with an all-in-one "Almighty Farming Tool" that can transform into any useful implement he wishes. Hiraku is then transported to a forest seemingly far from civilization. Here, he plans to build and farm everything from scratch—gradually developing the lifeless area into a thriving new society.

Thanks to the Fruit of Evolution, Seiichi Hiiragi's amazing new life in another world allows him to meet dependable allies and create formidable spells. His abilities catch the attention of Barnabus Ablitt, the principal of the Barbador Academy of Magic, who invites Seiichi to become a teacher at the institution. Coincidentally, Seiichi's classmates from Earth are enrolled there, which will lead to an awkward reunion if he is to meet them. Behind the scenes, however, an enigmatic cult called The Great Devil Order devises a sinister scheme to resurrect their deity and sacrifice the students of Barbador to hasten the process. As Seiichi's power is second to none, it is up to him to protect not only his friends but also the entire world from the looming darkness.