The story begins in a modern era where VR games are ubiquitous, having largely replaced traditional gaming formats. The protagonist, Kamijo Sora, a high school freshman and a self-proclaimed VR enthusiast, is about to embark on his journey in the highly anticipated VRMMORPG, "Astral Online." The game's premise involves players becoming adventurers on the Astral continent to defeat the Demon Lord Shaitan, but it also offers extensive freedom for players to pursue various paths, such as becoming nobles, merchants, or guild leaders. Sora's decision to play is due to the persistent pleas of his two best friends, Takamiya Shinji and Kozuki Shiro, who insisted on playing together.
After a humorous delay caused by Shinji oversleeping, Sora finally logs into "Astral Online." He is immediately struck by the game's incredible realism and detail, far surpassing any VR game he has played before. However, his starting experience deviates drastically from the norm. Instead of the advertised starting city, Sora finds himself in a dark, pillar-lined chamber. His initial exploration leads him to encounter a beautiful, silver-haired girl clad in dark armor, who is identified as the "Calamity Demon Lord" Shaitan. To Sora's shock, Shaitan attacks him, revealing a massive health bar, indicating she is a formidable boss. Despite being a level 1 adventurer with no class, Sora manages to evade and deflect Shaitan's attacks using skills honed from previous games. He even lands a blow, though it barely registers on her health bar. Shaitan, impressed by his tenacity, bestows upon him a "gift" before he is defeated.
Upon respawning, Sora finds himself back at the starting area, but with a surprising transformation: he has leveled up to 15 and acquired several new skills, including the unique skill "Lucifer." More astonishingly, he has been transformed into a beautiful, silver-haired girl. His friends, Shinji (now "Shin") and Shiro (now "Rou"), are initially confused, mistaking him for a cute girl. Sora reveals his true identity by exposing their personal secrets, convincing them of his predicament. He explains that the transformation is a curse from Shaitan, which can only be lifted by defeating her.
The trio then heads to the "Temple of Urd" to select their classes. Shin chooses Mage, and Rou chooses Knight. Sora, considering his unique situation and the game's mechanics, selects Enchanter, a class that buffs allies and debuffs enemies. He also discovers that his unique skill, "Lucifer," grants him a fourfold increase in skill point acquisition, allowing him to rapidly level up his Enchanter skills.
Later, while waiting for Shin and Rou, Sora witnesses them being defeated in a duel by a powerful player named Glen. Glen, a Knight, had been challenged by Shin and Rou, who wanted to prevent him from approaching Sora. Glen's subordinate, Gardo, insults Sora and his friends, provoking Sora. Despite being a beginner, Sora, now a level 17 Enchanter with enhanced skills, easily defeats Gardo in a duel. He then prepares to face Glen, but a mysterious, crimson-haired woman named Kirie intervenes, stopping the duel and revealing that Sora's weapon, the "Normal Sword," is near breaking. Kirie, a blacksmith, invites Sora and his friends to her shop.
Back in the real world, Sora discovers that his in-game transformation into a girl is permanent until the Demon Lord is defeated, and it has also affected his real-world body. He is now a silver-haired girl in reality. His sister, Shiori, helps him navigate this new reality and they decide to keep it a secret from their parents, who are currently on vacation. Shiori also reveals that Sora's silver hair and unique combat prowess have made him a viral sensation in the game's community, with players speculating about his origins and abilities. Sora, determined to defeat Shaitan and return to his original form, logs back into "Astral Online" with his friends, ready to face the challenges ahead.