The protagonist, Kurosaki Naoto, begins by lamenting his lack of friends, attributing it to his intimidating gaze. His mundane morning routine is disrupted by his mother's forceful wake-up call, followed by a typical breakfast with his father. At school, his fearsome appearance causes students to flinch, though some have grown accustomed to it. Among them is Shinomiya Yui, a beautiful and kind girl who, despite her apparent fear, consistently greets him. Their interactions are often interrupted by Sakuma Keiichi, a delinquent who harbors feelings for Shinomiya and resents Kurosaki's presence. Kurosaki, wishing to avoid further conflict, apologizes to Shinomiya.
During homeroom, the teacher is absent, and the classroom door is inexplicably locked. A popular and seemingly heroic student, Shirogane Hayato, calms the panicked class. Suddenly, the floor glows, and everyone is transported to a white space where a man claiming to be "God" appears. He informs the students that they have been summoned to clear a dungeon and will be granted powers. Among the students, Tamura Taichi, a light novel enthusiast, excitedly anticipates receiving "cheat" abilities. God warns them that survival is not guaranteed and then sends them away.
Kurosaki finds himself alone in a stone-floored area. He checks his status, revealing unique skills like "Truth Eye" and "Usurper," along with "Intimidation" and combat skills. A small fairy named Tia appears, intended to be his tutorial guide. Initially terrified by Kurosaki's appearance, mistaking him for an ogre, she quickly calms down after he reassures her. Kurosaki names her "Tia."
Tia explains the dungeon system, including levels, skills, and titles. Kurosaki learns his "Truth Eye" allows him to appraise anything and detect lies, while "Usurper" lets him steal enemy skills. He also discovers that "Intimidation" is amplified by his "Gaze of Terror" title. Tia explains that dungeons are formed from negative emotions and that clearing them is a task assigned by God. Kurosaki expresses his anger towards God.
The tutorial progresses with Tia explaining combat, magic, and the dungeon's structure, including its ten floors and safe resting rooms. Kurosaki learns about monsters, "magic stones" that can be converted into points for items, and a "box" for inventory. He successfully defeats a goblin, acquiring its "Virility" skill and leveling up. He reflects on his newfound determination to survive.
After the tutorial, Kurosaki begins exploring the first floor. He encounters and defeats various monsters, gaining new combat skills like "Spear Arts" and "Short Sword Arts." He finds a treasure chest containing a "Steel Sword" and a "Low Potion," which he uses to heal a minor injury sustained from a kobold. Kurosaki recognizes his own arrogance as the cause of his injury and vows to be more cautious. He discovers a resting room and plans to use it as a base for exploration. He also contemplates the fate of his classmates, deciding to help only those who genuinely seek assistance, using his "Truth Eye" to discern their sincerity. He later encounters a Hobgoblin and its subordinates, defeating them and further leveling up. After extensive exploration and combat, Kurosaki finds another resting room, where he encounters a classmate for the first time within the dungeon.