Awakening as Kang Hajun, a low-status student with a meager base mana of 0.9, is a nightmare. Worse still, this world is an unfinished webnovel where aristocratic power dictates everything, and Hajun is labeled a useless extra destined to disappear. Yet he possesses two hidden assets: an elite tactical mind and the 「Fault Gauge」, an ability that reveals the fatal flaws in any enemy. Seeking only a quiet life, Hajun alters key events behind the scenes. His actions trigger a massive butterfly effect, winning the devotion of the story's three main heroines: Lee Seol-ah, Shin Chae-won, and Han Yu-jin. With the original plot shattered and no future knowledge left, Hajun must step up to lead Squad Number Seven. Facing political conspiracies and apocalyptic rifts, the former extra proves that strategy alone can conquer destiny.