The story begins with the protagonist, Will Lancaster, regaining consciousness as a newborn. He experiences intense discomfort and a headache, leading him to cry uncontrollably. He quickly realizes he has been reincarnated into a fantasy world, likely as a baby, with his past life's memories intact. He finds himself in the care of a beautiful, kind mother, Lilyrelma Lancaster, and a stern but doting father, Windsor Lancaster, who appears to be a civil servant. Will's initial days are marked by the frustration of being unable to communicate or move freely, but he accepts his new reality and looks forward to learning the language and developing his abilities.
By the age of two, Will has learned to speak, much to his parents' delight. He discovers his name is Will Lancaster and that his family lives a comfortable life, suggesting a social standing above commoners due to the presence of a maid, Noina. He confirms the world is indeed fantasy when his mother uses healing magic on him after an injury. This sparks Will's fascination with magic, particularly healing magic, which he prioritizes due to his pragmatic RPG-influenced mindset of survival and resource management.
Meanwhile, Lilyrelma worries about Will's unusual quietness. Unlike other babies, he rarely cries and seems to understand conversations, often observing intently. She consults a doctor and Noina, who both assure her he is developing well, though Noina notes his intelligence and quiet nature. Lilyrelma also observes Will engaging in peculiar, seemingly nonsensical vocalizations that sound like incantations.
Will's understanding of the world expands as he learns about the three types of magic: Rune Magic (requiring magic circles and precise incantations), Divine Magic (invoked through prayer or petition), and Spirit Magic (requiring communication with spirits). He learns that magic requires innate talent and MP, making it exclusive to a select few. He also notes that the prevalence of magic has hindered the development of science and technology, with most problems solved through magical means.
Driven by his desire to master healing magic, Will begins experimenting. He discovers he can use healing magic on himself and, after some trial and error, successfully heals a withered tree, though it requires significant MP. He develops rudimentary research and reconditioning spells, learning to diagnose and treat ailments.
At the age of three, Will ventures out alone to the withered forest to continue his magical practice. He encounters a group of children bullying a girl named Mirei, who is labeled an "Imibito" (outcast). Will intervenes, defending Mirei and engaging in a fight with the bullies. He uses his healing magic to recover from their attacks, surprising them. Mirei, witnessing Will's kindness and his ability to heal, is initially hesitant to interact due to her status as an Imibito. Will, however, is unfazed and invites her to his home, but she flees, fearing it would cause trouble with her guardians.
Later, Will, now five years old, encounters Alfe Ninaka, a seven-year-old who was observing the earlier confrontation. Alfe, intrigued by Will's magic and his willingness to defend an Imibito, befriends him. Alfe reveals Mirei's location at a dilapidated orphanage on the outskirts of town. Will visits Mirei, who is living in harsh conditions and bears burn marks, presumably from abuse related to her Imibito status. Despite Mirei's initial fear and reluctance, Will offers her friendship and invites her to his home, but she flees again, citing potential conflict with her guardians. Will, determined to help Mirei, resolves to find a way to support her. He also learns about the world's geopolitical situation, where cooperation is necessary against threats like large wild beasts ("Nora") and dark creatures ("Kuro").
