Six-year-old Nola, trained by a mysterious mentor at the reclusive Ash Monastery, has developed astonishing monstrous strength. To protect the monastery and Nola, her mentor exhausted his magic power and is about to fall into eternal slumber, forcibly summoned by the divine realm. Carrying the token her mentor left behind, Nola descends the mountain: on one hand to retrieve her five foster brothers and sister who left home centuries ago, and on the other to find a way to save her mentor or awaken the monastery. Nola firmly believes the monastery is poor—in truth, her mentor follows the ancient "Vow of Poverty" and gave away all his wealth to maintain the protective barrier—so her siblings must be homeless and suffering out in the world. Thus, with only 12 copper coins in her pocket, a pouch of legendary holy potions (which she mistakes for candy beans), and a god-slaying greatsword taller than herself, she sets out on a journey to "rescue her brothers."
Upon entering the mainland, she smashes through the Holy Light Church's selection hall with a single sword strike, forcing out the most revered Supreme Holy Knight—the eldest brother, Arthur. After discovering that her big brother is actually wealthy beyond measure, Nola begins to doubt her mentor's words and resolves to personally verify whether the remaining brothers also "lied to her." Riding a newly subdued abyssal dragon hatchling, she charges into the Demon Realm to find her "possibly bullied" second brother. However, Lucian, the brutal demon king who rules the Demon Realm, instantly transforms into a fiercely doting big brother the moment his little sister pulls out holy potions to "rescue" him. An ultimate satisfying saga unfolds—a six-year-old cutie delivering a dimensional strike against the entire medieval continent, with her all-powerful big brother titans frantically escorting her from behind!