Yoshida Masaru, a 28-year-old Japanese salaryman, unexpectedly finds himself as a disembodied soul sphere in a pristine, white afterlife after a drunken fall. He learns from Tsuchi 25673888, a clumsy, rookie angel, that her mistake in dropping his soul caused him to awaken in the celestial realm, rendering him unable to undergo standard soul washing and reincarnation.
An ancient, authoritative god-like figure appears, offering Masaru a choice: soul destruction or reincarnation into a different world while retaining his memories. The god, surprisingly aware of Earth's light novel tropes, dismisses the idea of "cheat skills" or "harems," emphasizing the need for effort. As compensation for the celestial error, Masaru receives an "Item Box" (a spatial storage gift) and an "Otherworld Language Translation" skill. Furthermore, the god mandates that Tsuchi 25673888 accompany Masaru as his twin sister, Nicola, to support him and complete her own training. Their souls are partially merged, enabling telepathic communication.
Masaru and Nicola are reborn as Mark and Nicola, twins in the sword-and-magic fantasy world of Felgard. Their kind parents, Leo and Leona, run the "Traveler's Respite" inn in the town of Fatia. Nicola, retaining her celestial knowledge, acts as Mark's pragmatic advisor, explaining the world's mana-based magic system. While maintaining an angelic facade for others, she reveals a calculating, "parasitic" personality to Mark.
At age five, Mark, determined to live a more fulfilling life than his previous overworked existence, begins mana training. Nicola advises him that mana capacity expands by consistent depletion, especially during youth. Mark starts practicing earth magic, creating sand in a nearby empty lot. He is confronted by Gill, the gruff but ultimately kind owner of the lot, who initially suspects vandalism. Nicola's innocent act quickly disarms Gill, and Mark explains his magic practice. Intrigued by the superior quality of magic-made soil, Gill allows Mark to continue in exchange for the soil, which he plans to use for a garden, specifically for growing tomatoes, much to Mark's dismay.
Mark begins using earth magic to cultivate Gill's garden, learning that magic-grown vegetables are high-quality but expensive. Concurrently, Mark and Nicola navigate their family life, including their mother Leona's well-intentioned but disastrous attempts at "creative" cooking due to her lack of taste. Mark endures a particularly bitter soup, reinforcing his resolve to build a better life in this new world.
The arc sees Masaru transform from a passive, deceased soul into an active, five-year-old Mark, embracing his new life and magical abilities in a fantasy world, supported (and occasionally teased) by his former-angel twin sister, Nicola. He has found a purpose in training his magic and contributing to his new community, setting the stage for his future adventures.
