The story begins with the protagonist, Haru, a high school student who has dedicated three years to working multiple part-time jobs to save up 3 million yen for the highly anticipated VR game machine, "Arcadia." Despite alienating friends and worrying his parents, Haru achieves his goal just before graduation. He eagerly sets up the Arcadia, a full-dive VR system that immerses users in a virtual world through a sleep-like state.
Upon activating Arcadia, Haru finds himself in a stark white room with a single mirror. The mirror shows his reflection, which then speaks, welcoming him to "another reality." Haru is pulled into the mirror and experiences a disorienting transition, falling through the sky and into the sea before landing in a grassy field. A disembodied female voice explains that this world is his "second home." He notices his clothes have changed to a simple starting outfit, and a mirror appears again, showing his avatar, which differs from his real self only in eye color. He steps through the mirror, ready to begin his adventure.
Haru awakens in darkness, encased in a crystalline substance. A faint light appears, and with a powerful sound, the crystal shatters, freeing him. He finds himself in a cave, and upon regaining control of his body, a user interface appears, displaying his name, "Haru," and basic stats like HP and MP. He quickly familiarizes himself with the system, noting the radar and the unusual 25:00 time display.
Emerging from the cave, Haru enters a dimly lit tunnel and finds himself in a small room with a peculiar glowing crystal. He then encounters his first enemy: a small, rock-like golem. Initially attempting communication, Haru quickly realizes it's hostile. Despite his lack of weapons, he tries to evade its slow but surprisingly fast attacks. The golem's immense strength is demonstrated when its arm easily shatters the rocky ground. Haru, realizing he's outmatched and in a potential "lose event," decides to flee. However, the golem seals his escape route with rising rock walls, confirming his suspicion that this is a scripted defeat.
Instead of surrendering, Haru decides to fight. He dodges the golem's attacks and attempts to land blows, but his unarmed strikes are ineffective. The golem then reveals its HP bar and name, "The Chosen Stone Doll." Haru realizes this might not be a guaranteed loss event and that he can damage it. He engages in a prolonged, difficult battle, eventually defeating the golem after three hours. He receives two titles: "One Who Throws Themselves into Conflict" and "One With an Unyielding Heart."
After the battle, Haru enters a more elaborate chamber with five pillars, each bearing a different emblem: a sword, a heart, wings, and a castle. Interacting with these pillars reveals information about the game's four factions: Istia (sword, conflict), Vestor (heart, peace), Nortalia (wings, luck), and Sortalm (castle, wealth). Haru, drawn by the low player count and the potential for involvement in future wars, chooses Istia.
Upon selecting Istia, Haru is teleported to a forest clearing and immediately collides with a girl. He learns she is a new player named Sora. They discover they are both new to the game and chose the same faction, Istia, which is noted as being unpopular. Haru, impressed by Sora's kindness and appearance, agrees to travel with her.
They venture into a mushroom-infested forest. Sora, despite her initial fear and lack of combat skills, proves to be a supportive companion. Haru, with his quick reflexes and combat experience from part-time jobs, protects Sora while she focuses on healing. They encounter various mushroom-like enemies and level up, with Haru specializing in agility and dexterity, and Sora focusing on mind and luck for magic. Haru acquires skills like "Multiple Weapon Aptitude" and "Quick Change," while Sora gains "Heal Light."
Their journey leads them to the forest's boss, the "Host of Mushrooms." Haru's aggressive, unconventional fighting style, involving throwing weapons with his "Quick Change" skill, overwhelms the boss and its summoned minions. Sora, initially intimidated by Haru's "berserker" mode, witnesses his victory and is impressed. They are then teleported to the main city of Istia.
In the bustling city, Haru and Sora attract attention as new players in the unpopular faction. Sora, embarrassed by their close proximity during the teleportation, quickly logs out. Haru, feeling a sense of loss, also logs out.
The next day, Haru returns to the game, now level 17, and heads to the beginner area, the "Plains of the Horizon." He struggles with inventory management due to his equipment choices and the game's weight system. He also faces a challenging encounter with a horde of "Fool Boars," whose relentless charges and high stats make them difficult to defeat. Haru's previous death in the forest was due to a surprise attack by the area boss, "Earth-Buried Great Boar," which he vows to defeat with Sora's help.
Sora, determined to find Haru again, logs back into the game and successfully reconnects with him. They decide to tackle the Fool Boars together, with Haru acting as the primary attacker and Sora as the healer. They discover Sora has acquired a new skill, "Healer's Tenet," further solidifying her support role. Haru, having learned from his previous encounters, plans to strategically defeat the boar boss.