The protagonist, Haihane Aki, finds himself abruptly transported from a convenience store to a stark white space. There, he encounters a white-bearded old man who informs him that he has been chosen as a hero to be summoned to another world. Aki, initially bewildered and annoyed by the arbitrary nature of his selection and the old man's dismissive attitude, learns that this is a common process in larger worlds. He is then presented with the opportunity to choose skills by rolling a large, six-sided die.
Before rolling, Aki requests and is granted the ability to check his status and practice rolling the die. His status reveals him as "Haihane Aki, LV0 (Spiritual Body), Race: Hero," with abilities including "Room Creation" (unlocked) and skills like "Appraisal LV Extreme," "Hero's Charisma," "Hero's Blessing," and "Potential Up LV Extreme." He learns that "Room Creation" will activate upon his arrival in the new world.
Aki then engages in a negotiation with the old man regarding the skill selection. He proposes a high-risk, high-reward scenario: if he rolls a six, he receives twelve skills and two unique skills; otherwise, he receives only one skill and six negative skills. The old man, intrigued by Aki's audacity and understanding of the world's mechanics, accepts the bet, with the condition that if he rolls anything other than a six, he receives zero skills and six negative skills, while a six grants him twelve skills and two unique skills. Aki, aiming for a specific skill, chooses "Thought Calculation LV Extreme" after reviewing a vast list of skills, including those related to luck. He believes that precise calculation and practice can guarantee a six.
During the die roll, the old man attempts to interfere by having the space itself intervene, causing the ground to dent. However, Aki's "Appraisal" skill, which he had been granted, allows him to foresee this. He reveals that the space itself has consciousness and that the old man's "promise" not to interfere did not include the space itself. Despite this, Aki's calculated throw results in a six. The old man, initially shocked by Aki's composure and foresight, is further flustered when Aki reveals he used "Appraisal" to understand the space's mechanics. The old man, regretting his oversight in not removing the temporary "Appraisal" skill, is forced to honor the deal.
As a parting gift, Aki uses his "Dark Summon" unique skill to force the incredibly foul "Strawberry Pumpkin Burdock Melon Bread" into the old man's mouth before being transferred to the new world.
Aki awakens in a deep forest, realizing he has been "mis-transferred" due to his prolonged skill selection. His status now shows LV1 and a variety of skills, including "Magic Operation," "Magic," "Magic Power Up," "Danger Perception," "Presence Perception," "Magic Beast Tamer," "Body Reinforcement," "Magic Perception," "Throwing Technique," "Healing Magic," "Alchemy," "Universal Resistance," and unique skills like "Dark Summon," "Deception God" (with various sub-abilities), "Material Transfer," "Absorption," and "Item Box." His ability "Room Creation" is now LV1.
He quickly learns the harsh reality of this world when he encounters powerful goblins, far stronger than his current level. Using his "Deception God" skill, he narrowly escapes by tricking a goblin into attacking its ally. He then creates a "Room" using his "Room Creation" ability, which manifests as a "Front Door" leading to a "Foyer." Inside, he meets Haru, a grey-haired woman who identifies herself as the "Room Manager" born from his "Room Creation" ability. Haru, who calls him "Master," informs him about the world's harshness and the importance of strength.
Aki, realizing the danger, begins training in a "Training Room" created by his ability. He also creates other rooms: a "Living Room" with a basic kitchen, a "Ranch" for food, a "Farm," a "Water Source," a "Bedroom," an "Armory," and the "Training Room." He discovers that the "Ranch" animals have varying "ranks" corresponding to their strength and taste, with weaker ones being near the entrance and stronger ones further away. He also learns about "Room Points" (RP) needed to create and customize rooms, which increase daily and with skill level-ups.
Aki struggles to gain strength by fighting high-level goblins in the Training Room, as it's the only opponent he can currently appraise and summon. He learns that the world's environment changes drastically and rapidly, and its inhabitants are adapted to these changes. He also discovers that his "Room Creation" ability operates through a "Room Menu" and requires RP. Haru, despite her bluntness, guides him, and Aki eventually names her "Haru" (Spring), connecting it to his own name, Aki (Autumn). He learns that Haru was born from his "Room Creation" ability and possesses knowledge of his past actions and his abilities.
The narrative concludes with Aki facing the daunting reality of his situation, realizing that escaping the "Front Door" and surviving in this harsh world will take a significant amount of time and effort, as even the "weak" goblins he initially fought are incredibly powerful compared to his current level. He continues to train, aiming to increase his strength and explore the world, guided by Haru.
