The story begins with Haruna, a middle-aged woman from Osaka, abruptly finding herself in a grassy field, having seemingly died in an accident. She discovers she has been reincarnated into a younger, more attractive body in a new world. A self-proclaimed goddess explains that Haruna, identified as an "Osaka Obaachan" (a term for a boisterous, middle-aged woman), is considered the "strongest human" and has been chosen to be reborn as the strongest young female knight in another world. Haruna's initial confusion and desire to return home are met with the goddess's explanation that her mission is to spread okonomiyaki, a Japanese savory pancake, to improve the world's food situation.
Upon arrival in this new world, Haruna finds herself in a grassy plain, not the "New World" district of Osaka she humorously envisioned. Her immediate concern is her lack of money, though she finds candy in her bag. She soon encounters a group of pig-like creatures, orcs, who see her as an easy target. To her surprise, Haruna possesses incredible physical strength, easily defeating the orcs with bare hands and playful "tsukkomi" (comedic retorts) and "boke" (foolishness) actions, akin to scolding children. The orcs, intimidated by her overwhelming power, surrender and offer her jewels.
Haruna eventually reaches the walled town of Allsuck. Her unusual attire, a lion's mane-like outfit, leads the guards to believe she is a formidable warrior. At the adventurer's guild, she meets Loufa, a small, bob-haired receptionist. Haruna's inquiries about train stations are met with confusion, but Loufa, recognizing her otherworldly origin, explains the world's basics. Haruna learns that okonomiyaki and other familiar Japanese items are non-existent. Loufa suggests she become an adventurer, and Haruna, after some negotiation, agrees to pay the guild registration fee with the jewels she received.
Upon checking her status, Haruna discovers her stats are extraordinarily high, with unique skills like "Okonomiyaki Magic" and "Boke/Tsukkomi" stats, baffling Loufa. She then purchases a sword and, following Loufa's advice, heads to a nearby dungeon to earn money by hunting monsters for their magic stones. Haruna's exceptional combat abilities allow her to clear floors with ease, quickly accumulating a significant amount of gold.
With her newfound wealth, Haruna opens "Haru-chan's Adventurer's Department Store" within the dungeon, selling food and healing items. Her kindness and generosity, particularly her habit of giving out candy (which she can produce infinitely using her dimensional manipulation magic), earn her the nickname "Candy-distributing Angel." The store becomes a vital resource for adventurers, offering a place to rest and resupply. Haruna then innovates by creating and selling okonomiyaki and negiyaki, adapting them to local ingredients and tastes. These dishes, along with her other offerings, become incredibly popular, revolutionizing dungeon exploration and making "Haru-chan's" an essential hub.
As her business thrives, Haruna hires more staff, including a devout priestess named Kokon, who eventually becomes her right-hand woman. The business expands to a second location in town and eventually operates 24/7 in the dungeon. However, the demanding nature of the business leads to a crisis when several key employees, including Kokon, decide to leave to form their own adventurer party, seeking to earn money through traditional dungeon delving. This forces Haruna to re-evaluate her business model and seek new staff, highlighting the constant challenges of managing her burgeoning enterprise in this new world.
