The story begins with Nishiyama Kouta, a 28-year-old man who has been living a reclusive life for two years after quitting his stressful sales job due to depression. He lives in a cheap studio apartment and spends his days in isolation, subsisting on savings. His only regular interaction is feeding a crow he affectionately calls Kirk, a ritual that has helped him feel less alone.
One day, a severe traffic accident occurs outside Kouta's apartment. A car crashes through the block wall bordering his small yard, tragically killing both Kouta and Kirk, who he shielded with his body.
Kouta awakens in a white, featureless space, where he meets a woman who identifies herself as a guide for souls awaiting reincarnation. She informs him of his death and explains that he will be reborn into a new life. Kouta, surprisingly calm, inquires about the possibility of reincarnation into another world. The guide confirms this, and Kouta expresses his sole wish: "health of mind and body, and a peaceful life." A young boy, seemingly a divine being, interrupts the process, playfully altering Kouta's fate by granting him memories and sending him to a harsher environment. The guide, unable to fully correct the boy's actions, bestows additional blessings upon Kouta and a small light that had also been present.
Kouta awakens again, this time in the hollow of a massive tree in a lush, unfamiliar forest beside a clear lake. He retains his memories and finds himself in a new body, feeling healthier and more robust. Kirk, now larger and possessing three legs, is also present. They discover they are in a new world, and Kouta, with his newfound "health," is optimistic about their survival. They find sustenance in the tree's fruit and water from the lake.
Their exploration leads them to a forest with graying trees, hinting at a darker, more dangerous area ahead. They encounter a black deer with sharp, sword-like antlers. Kouta, protected by his enhanced health, easily withstands an attack. The deer, in fear, breaks off an antler and offers it to Kouta as a tool, which he accepts. Kirk, meanwhile, displays magical abilities, creating fire.
As they continue their journey along a river, they encounter a young woman named Abigail "Abby" Ambrose, a renowned "Sage" from another world who has also been transmigrated. Abby, who identifies as a transgender male, has escaped a forced marriage and a life of societal expectations. Kouta, despite his initial shyness and lingering social anxiety, recognizes Abby as another transmigrator and a fellow "otherworlder." Their shared experience and the presence of Kirk, who can now use magic, mark the beginning of their intertwined adventures in this new world.
