Kanami Aikawa awakens disoriented and terrified in a dark, labyrinthine corridor, with no memory of his past. After fleeing a giant insect, he encounters adventurers battling a massive wolf. Desperate for help, Kanami is cruelly betrayed by their leader, wounded and used as bait. Left for dead, a mysterious "Skill '???'" stabilizes his mind, allowing him to kill the wolf. This trauma leads to the discovery of a game-like "system" overlaying his reality, featuring a "Status" screen, "Skills" (Swordplay, Ice Magic, Dimension Magic), and an "Item" inventory. He learns to "Observe" monsters and uses "Dimension Magic" for spatial awareness, adapting to the brutal pragmatism needed for survival by looting and efficiently defeating monsters.
His growing confidence is shattered when he's poisoned by a "Big Frog," and his antidote fails. Critically low on HP, Kanami uses advanced Dimension Magic to locate a "managed zone" where he encounters a wealthy adventurer party. Among them is Rustyara, a beautiful but unsettling young girl who can see Kanami's status. She expresses strange envy before healing his poison and restoring his health. Later, Rustyara secretly infiltrates Kanami's inn room and forcibly levels him up to Level 4, explaining he is her "candidate." Her manipulative actions leave Kanami deeply unnerved.
Kanami escapes the labyrinth and arrives in Fuziyards, a noble-centric "Knight Nation." He learns about the "Five Nations" and the "Hundredth Trial" legend (granting any wish). Discovering his system is unique and Fuziyards too expensive, he moves to Wald, a cheaper, adventurer-focused nation.
In Wald, Kanami adopts the alias "Christ Eurasia" to avoid Rustyara and secures a tavern job. He uses his "Observe" skill to gather information. He encounters Diablo Sis, a young boy with incredibly high-potential magic skills but stuck at Level 1, struggling to find a party. Seeing Diablo's immense potential, Kanami strategically befriends him, offering food and feigning regret. Diablo, desperate for a partner, asks Kanami to form a party, which Kanami accepts, setting conditions. The system confirms "Diablo Sis joined the party. Party Leader is Kanami Aikawa."
Their first labyrinth dive as a party is highly successful. Kanami's advanced Dimension Magic provides unparalleled scouting and positioning, while Diablo's "Flame Arrow" magic is a powerful, laser-like attack that instantly vaporizes monsters. Kanami, terrified by Diablo's overwhelming power, recognizes their synergy. He lies about his Dimension Magic to maintain his unique advantage and ensure Diablo's reliance. As they clear monsters with ease, Kanami realizes Diablo, his first friend in this isolating new world, has become an unexpected emotional anchor. The arc concludes with Kanami, no longer alone and with a powerful partner, poised to tackle the labyrinth more effectively, driven by his ultimate goal of returning home.
