Chapters 3-12 of the light novel introduce two main characters who are abruptly transported to a fantasy world: Kenzaki Kamui, a seemingly ordinary but talented high school student, and Tanaka Taro (a pseudonym), a middle-aged salaryman with a chuunibyou (eighth-grader syndrome) complex.
Chapter 3 begins with Kamui being walked home by two admiring girls, Kirara and Kisara, when he is suddenly engulfed in light and disappears. Simultaneously, Tanaka, who was harboring bitter thoughts about Kamui's popularity, is also swallowed by a mysterious darkness and vanishes.
Chapters 5-8 detail Kamui's arrival in the Kingdom of Pudding. He finds himself in a secret chamber where a Hero Summoning ritual is being performed. The ritual, a stolen and modified technique from the neighboring Gokuri Republic, is unstable. Kamui is summoned as the Hero, chosen for his high potential and imbued with immense power by the gathered mages. Princess Lara of Pudding explains the kingdom's plight: they are under attack by monsters and their military is outmatched. Kamui, initially bewildered, becomes exhilarated by the prospect of having such power and readily agrees to help.
However, their conversation is interrupted in Chapter 8 by a report that all magical power in the capital has vanished. This event is explained in Chapter 9 as a consequence of the summoning ritual. The ritual, designed to create the Hero Kamui, was supposed to deactivate, but unexpectedly, Tanaka was also summoned. The faulty ritual, desperate for power to stabilize, drew upon the abundant magical energy from Kamui's original world, Earth, to enhance Tanaka. This massive energy drain caused the magical disruption. Princess Lara, revealed to be a shrewd and calculating individual, focuses on damage control, while General White, a gruff but pragmatic military man, argues with her about the kingdom's flawed policies. Kamui is left bewildered by the unfolding chaos.
Chapters 10-12 shift focus to Tanaka's perspective. He awakens in the Pudding Kingdom and is found by General White, who recognizes his unusual attire and otherworldly nature. Tanaka is brought to General White's residence, where the General explains the situation. Tanaka, still reeling from his sudden displacement and his chuunibyou tendencies surfacing, learns about Hero Summoning and the kingdom's troubles. He is shocked to discover he is not the summoned Hero, as Kamui was. General White, recognizing Tanaka's precarious situation as a foreign anomaly, advises him to leave the kingdom for his own safety, as he would likely be imprisoned if discovered. He suggests Tanaka head east towards the Haru Empire.
Chapters 12-37 chronicle Tanaka's journey and adaptation to this new world. He is given provisions and an "item box," a magical storage device. His initial attempts to use magic, learned from a low-level spellbook, result in overwhelmingly powerful and uncontrollable effects, like an inferno from a simple "Ignition" spell and a tidal wave from a "Water" spell, highlighting his immense, albeit unrefined, magical potential. He inadvertently defeats a "black-horned rabbit" which grants him experience points, leading him to believe he can level up by hunting. He spends weeks in the mountains, hunting these rabbits and gaining levels, though his core stats remain incredibly low, earning him the title "baby-level." He also acquires a "Sword Skill" and a peculiar "Beloved by Many" skill, which seems to amplify his magic.
Tanaka eventually reaches the city of Hazama in the Haru Empire. He registers with the Adventurer's Guild, where he learns about the world's structure, the existence of guilds, and the ongoing food shortage caused by the earlier magical disruption. His immense item box capacity surprises the guild receptionist. He sells a massive quantity of rabbit carcasses for a significant sum, securing his immediate financial stability. He then decides to pursue magic further, acquiring higher-level spellbooks from a researcher named Omoi, who is working on a device to restore soil magic. Tanaka's magic, however, remains wildly uncontrollable, causing localized destruction.
A new threat emerges: bandits are plaguing the trade routes. Tanaka, despite his low stats, is inadvertently drawn into a situation where he is forced to defend himself and a merchant caravan. His "Ignition" spell, used defensively, incapacitates the bandits in a gruesome manner, leaving him horrified but also realizing his magic's destructive potential. The merchant, Echigoya, recognizes Tanaka's unusual abilities and potential. The narrative sets up future conflicts and Tanaka's ongoing struggle to control his power and survive in this new world.
