The story begins with Nonomiya Ippei, an ordinary high school student, being unexpectedly summoned to another world by a mysterious rainbow vortex. Embracing his otaku upbringing, Ippei immediately deduces the situation as a summoning and, with a mix of excitement and a touch of regret for not being better prepared, dives into the vortex. His parting words to his parents are a chaotic, excited note about being summoned and the possibility of a harem.
On the other side, a cloaked figure, later revealed to be the 65-year-old genius mage Ryuryu Shendelfer, has successfully revived the lost art of summoning magic. However, the summoning process is fraught with peril due to the unpredictable nature of the magic and the loss of control techniques. Ryuryu, despite her genius and extensive preparations, is overwhelmed by a sense of dread as the summoning concludes.
Ippei emerges from the vortex, landing ungracefully and immediately expressing his desire for a "choroin" (an easily swayed heroine) and cheat abilities. He is bewildered to find his summoner is not a beautiful maiden but an elderly woman. Ryuryu, initially terrified by the unexpected human summoning, quickly realizes she has made a grave error, potentially kidnapping a noble. Ippei, however, is unfazed, his mind filled with fantasies of adventure, harems, and becoming a hero.
The initial interactions between Ippei and Ryuryu are filled with comedic misunderstandings and Ippei's often insensitive but well-meaning nature. Ryuryu, despite her age and past regrets as a former court mage who was framed and exiled, finds herself increasingly drawn to Ippei's naive optimism and his seemingly incredible abilities, which she misinterprets as signs of a destined hero. She agrees to teach him magic in exchange for his continued stay, though her true motivation is a desperate desire for companionship.
Their first adventure takes them to the Spirit Forest in search of dragons, a quest Ippei eagerly pursues. Ryuryu, initially hesitant due to her age and lack of combat readiness, is dragged along by Ippei's relentless enthusiasm. They encounter a massive, seemingly invincible ancient wolf that Ryuryu's magic fails to affect. Ippei, despite his initial lack of powers and his own comical fighting style, manages to inadvertently "defeat" the ancient wolf by causing it to retreat due to its sheer size and Ippei's persistent, albeit nonsensical, attacks. This encounter solidifies Ryuryu's belief in Ippei's destiny.
Upon arriving in the capital city of Veran, they head to the Adventurer's Guild to register. Ippei's boisterous declaration of wanting to build a harem and his bizarre, theatrical fighting stances immediately draw the attention and ridicule of the seasoned adventurers. He is challenged to a duel by Valery, a handsome knight candidate who is infatuated with his senior, Rochel. Ippei, in his characteristic fashion, turns the duel into a bizarre spectacle of self-imposed handicaps and philosophical pronouncements about heroism and dreams, ultimately baffling everyone present.
The story introduces Rochel and Valery, a pair of adventurers with their own complicated relationship. Rochel, a strong-willed woman, is initially dismissive of Ippei's antics, while Valery, a knight with a hidden romantic streak, is intrigued by Ippei's charisma and his seemingly unwavering belief in his own destiny. Their interactions highlight the contrast between Ippei's fantastical worldview and the more grounded realities of this new world.
The chapters conclude with Ippei and Ryuryu embarking on their next adventure, heading towards the Adventurer's Guild to officially register and begin their journey. Despite the chaotic and often absurd nature of their interactions, a unique bond is forming between the summoned boy and the aging mage, setting the stage for future exploits in this new world.
