A lonely, honest man dies at the end of a life spent in solitude. Facing a goddess, his final wish is peculiar and direct: reincarnate him as a fat, inseminating middle-aged man so that in his next life, he can be surrounded by many kind people who love him as the center of a large harem. His request granted, he is reborn into a world of swords and magic as Genji, a kind-hearted old man with a particular fondness for mature women. Accompanying him on his journey is the goddess, now transformed into a fat bird with a sharp tongue who serves as his straight man and guide, named Pinoko.

Genji is an extraordinarily overpowered protagonist with abilities that include time manipulation and great physical strength, making him effectively invincible in this new world. Rather than seeking conflict, his primary goal is to build a loving family by marrying women from every species he encounters. His approach is direct yet surprisingly consensual, driven by a desire for genuine connection and procreation rather than cruelty. Despite his unbeatable power, the narrative focuses on absurd comedy and explicit situations as he travels, saving the weak and crushing the strong without any significant character growth or challenging foes. The story unfolds across a fantasy realm where he meets a diverse cast of potential brides. These include Aesis, a dark-skinned elf archer; Artisia, a cruel elf racial purist who wears a crown; Lizabella, a noble; Cindy, a woman with a ponytail; Labia, a maid with a headband; and Mimosa, another woman of nobility. He also encounters non-human characters such as the Orc Queen and the One-Eyed Black Dragon. The manga chronicles his comedic and explicit adventures as he wanders from place to place, using his overwhelming power to solve problems and add new wives to his growing harem.