The story begins with Fujii Kanade, a 41-year-old woman, receiving a breast cancer diagnosis. The treatment, including chemotherapy, causes her hair loss, skin changes, weight gain, and a general loss of interest in her former life. Despite the doctor's reassurances, her condition worsens, with metastasis and a two-year battle ending in her death.
However, Kanade awakens in a dense forest, realizing she has been reincarnated or transferred to another world. She discovers she is now a 15-year-old with a status screen. Her stats show high MP but no magic ability, though she possesses useful skills: "Home Summon," "Language Translation," and "Literacy." Her immediate concern is survival, and she uses "Home Summon" to create a small cottage with a farm and an apple tree. The house is well-equipped with food, amenities, and even a manual explaining its "cheat" properties: infinite supplies within its confines, health and stamina recovery effects from its food, and the ability to grow with her level.
Her initial joy at this new life is shattered when a monstrous spider-like creature attacks the perimeter of her home. The house's barrier repels the creature, and its own attack backfires, destroying it. This confirms her new reality and the presence of dangerous monsters. She feels trapped but is buoyed by the house's ability to level up. The next day, she finds mayonnaise in her refrigerator, indicating her status has increased to level 2. Over the next three months, her level rapidly rises to 90, and her home expands into a large house with an extensive farm, orchard, and even a library. The library reveals the "Demon Forest" she inhabits is a dangerous place, with monster levels escalating the deeper one goes, and her location is the deepest, most inaccessible part.
To escape, Kanade decides to "summon" another house, which leads to the creation of a "village." This expands her territory but also burdens her with the upkeep of multiple farms. Craving variety in her diet, she wishes for meat and fish. A colossal dragon appears, drawn by the smell of her cooking. Kanade, using her language translation skill, communicates with the dragon, named Richmond, who is a former Dragon King. He is impressed by her food, particularly her udon and tempura, and offers to take her to a human city in exchange for her cooking.
Richmond reveals the world's political landscape: a tense cold war between humans and demi-humans (beastmen, dwarves, elves) stemming from past enslavement. He warns Kanade about the greed of humans and offers her a safe haven in her village, protecting her in exchange for her continued hospitality. He also helps with her farm work using magic.
Later, Kanade's home evolves into a grand Western-style mansion. Richmond, now living with her, takes her to a human city. They encounter a street thief and witness the city's rougher side. Richmond, using his spatial magic, purchases three barrels of alcohol. Upon returning to the forest, they find two young, emaciated children near the village entrance, attacked by a boar-like monster. Richmond rescues them, and Kanade decides to take them in. She discovers her house's food has potent healing and nutritional properties, quickly restoring the children's health. The younger twin, Louis, reveals he and his brother, Arthur, were abandoned. Kanade, touched by their plight and the injustice they faced, embraces her role as their caretaker, further solidifying her new life in the Demon Forest.
