The story begins on Tris's fifteenth birthday, the age of adulthood in this world. Tris, the third son of the minor Baron Lyano, lives in the modest territory of Lyano, a place often derided as a provincial town. Despite his family's humble status, Tris is filled with gratitude for his parents' unwavering support of his lifelong dream: to become an adventurer. Unlike most nobles who are expected to become independent, Tris eagerly anticipates this day, envisioning a life of freedom, travel to the seven labyrinth cities, and perhaps even encountering a divine dragon. His parents gifted him a mysterious, jet-black magic sword on his eighth birthday, a weapon whose power is undetectable by appraisal magic, suggesting it was acquired at a low price. Tris has dedicated himself to mastering swordsmanship and basic magic, training alongside his elder brothers, Fine and Selo, to honor his parents and prove worthy of his magic sword.
His younger sister, Mimil, interrupts his morning routine, reminding him of his departure. A farewell party was canceled at Tris's request, much to Mimil's disappointment. As Tris prepares to leave, his father inquires about his luggage. Tris, confident in his magic sword, states he needs little else. His brothers tease him about his devotion to his sword, but the conversation is cut short by the urgent arrival of the butler, Sebastien. He announces the unexpected early arrival of Princess Snow, the "Blue Saint" of the Einheit Kingdom, known for her potent healing magic. The household is thrown into a flurry of preparations.
Tris departs his home, bidding farewell to his family. He explains that he won't be leaving the town immediately; first, he must register at the Adventurer's Guild and pass the certification exam to become an apprentice. Only after achieving the rank of E-rank adventurer can he truly venture beyond the town. He also mentions waiting for his mother's return from the capital. His family expresses their love and concern, urging him to be careful and to consult them if he faces difficulties. Mimil, tearfully, makes him promise not to get injured.
Tris arrives at the "Gateway Inn," a modest but clean and well-regarded establishment run by Mrs. Bata, the sister of the family cook. He reveals his intention to become an adventurer, a path only open to commoners. He willingly relinquishes his noble status, a prerequisite for becoming an adventurer, which brings him joy. He then heads to the Adventurer's Guild.
At the Guild, Tris meets Ridley, a young guild staff member, and Nevan, a gruff, high-ranking adventurer with a scar on his cheek. Nevan, intrigued by Tris's magic sword, offers to conduct his adventurer certification test immediately, waiving the usual apprentice period due to Tris's apparent skill. The test begins with a physical challenge: carrying a heavy pack for twenty laps around the training grounds, which Tris completes with surprising ease. He then undergoes further simple tests of agility, reflexes, and basic sword handling, all of which he passes. Nevan, impressed by Tris's abilities and his magic sword, decides to grant him an exemption from the apprentice rank, allowing him to start as an E-rank adventurer.
Nevan then proposes a mock combat session to assess Tris's true skill. Ridley expresses concern about Tris's safety, but Nevan insists on testing him. Tris, wielding a training sword, faces Nevan, a clearly experienced fighter. Despite Tris's impressive swordsmanship, which surprises both Nevan and Ridley, he is ultimately outmatched and defeated. Nevan acknowledges Tris's strength, noting he is far more skilled than Nevan was at his age, and officially declares him an E-rank adventurer.
The next day, Tris accepts his first quest: to hunt "Horn Rats" in the rural outskirts of town. He prepares lightly, relying on his basic magic for utility. While observing the target area, he discovers a larger-than-expected colony of Horn Rats. Before he can report back, he spots a lone figure, a young woman, walking carelessly towards the colony. Tris rushes to her aid, intercepting the approaching Horn Rats. He swiftly dispatches them with his magic sword. The young woman, who introduces herself as Yui, is revealed to be a magic user, though her initial reaction is one of panic.
Suddenly, a dazzling light engulfs the area, and the remaining Horn Rats are annihilated. The source of this overwhelming magic is a mysterious girl wearing a butterfly mask, who introduces herself as "Ponton." She disappears as quickly as she appeared, leaving Tris bewildered. He returns to the Guild to report the incident, but to his surprise, his account of the masked girl's intervention is believed, as similar reports have surfaced recently. He receives payment for the Horn Rats he defeated, along with compensation for the ones eliminated by the masked girl.
Later, back at the inn, Tris encounters the masked girl again, who is revealed to be Yui. She confesses she is not from this world but was summoned as one of ten "Heroes" from another country. She explains her struggles with magic, her expulsion from the Hero group due to her limited abilities and a tragic incident involving another Hero, and her use of a "recognition inhibition" mask to remain unnoticed. Tris, intrigued by her story and her unique abilities, offers to form a party with her. Yui, touched by his kindness and acceptance, agrees. Tris, realizing the potential of her abilities and his own unique resistance to magic, feels a sense of purpose and the beginning of a new journey.
