The story begins with Gallia Braizel, the lord and head of the prestigious Braizel family, and his wife Meriena, a skilled mage, gazing at their newborn son, Reus. They harbor immense expectations for him, believing he will possess extraordinary talent. However, their hopes are shattered days later during a traditional ritual to measure Reus's magical aptitude using a divine tool called a "divine tool." The tool, which typically displays a reading, malfunctions, spinning wildly before settling on a mere "3." Gallia, enraged and disbelieving, declares his son dead from illness and orders the ritual's attendees, including the priest, to keep the true result a secret.
Unbeknownst to them, Reus is not dead but has been reincarnated with the memories of a great sage named Aristoteles. He was deliberately discarded by his father's subordinate, who, hesitant to harm an infant, hired dark merchants to abandon Reus in a box near the dangerous "Demon Realm Forest." Reus, realizing his low magical aptitude was due to the divine tool being a magic item he himself created in his past life, and that his true aptitude is 1103, escapes the box. He quickly encounters an Orc, whom he dispatches with a concentrated blast of magic, but this depletes his meager infant mana. A Manticores then appears, but Reus is saved by the timely arrival of his former favorite weapon, the sentient staff "Lintworm."
Lintworm, capable of telepathic communication, helps Reus survive. Reus, now able to absorb ambient mana, strengthens his infant body and, with Lintworm's assistance, finds a mother wolf who has recently given birth. He cunningly infiltrates her den and drinks her milk, forming a bond with her and her pups. Over the next month, Reus grows significantly, learning to walk and even speak, all while continuing to absorb mana and strengthen himself. He becomes like a brother to the wolf pups.
As the wolf pack faces an invasion by giant spiders, led by a formidable "Northern Lord," Reus, despite his infant form, decides to fight alongside his adopted family. He wields Lintworm, now in sword mode, and proves instrumental in the battle. During the fight, the mother wolf, the "Southern Lord," is captured by the Northern Lord, a colossal spider. Reus, using Lintworm in its powerful breath attack mode, obliterates the Northern Lord, saving the mother wolf and the pack. He then uses an anti-poison spell to heal her from the spider's venom.
After the battle, Reus decides to leave the forest, as his presence is causing discord within the wolf pack. He bids farewell to the wolf pups and the mother wolf, who, though still denying him as her child, shows affection. Reus, now capable of independent survival and with Lintworm, plans to become an adventurer in human society, seeking freedom and avoiding the complications of his noble birth.
Meanwhile, Gallia and Meriena, having learned from a priest that their true son's magical aptitude was far higher than initially believed (over 1000, not 3), realize they made a grave error in discarding him. They are informed by a Saint that a great sage is prophesied to be reborn in this era, and they suspect their discarded son might be this individual. Driven by fear of ruin for their family name, they rush back to the Demon Realm Forest to search for him, though the chances of him surviving are slim.
