《Synopsis》 ——A world where the quality of one's ability determines human value. In this place, the rank shown by the "Measurement Crystal" is the absolute order and the chain of rule.

The "S" rank at the peak unreachable by commoners, the "SR" rank that leaves a name in history, and the "EX" rank, a non-standard singularity. At the "National Ability Merit Academy," a fully residential stratified society established as a microcosm of this world, five boys and girls gathered, each burdened by their own destiny.

The intellectual S-rank who loves books, Michiya Honshi. Mirai Hariyama, a B-rank who hides knowledge equal to Michiya behind a soft exterior that gets along with everyone. Hasami Ryoba, a girl trembling in loneliness, acting as an "F-rank" out of a terrifying fear of being disliked. Shizu Yozora, a mysterious F-rank who wishes to hurt no one and acts cheerfully using gaming slang. And Sui Mikae, the symbol of peaceful daily life, possessing no power to fight amidst the whirlpool of abilities.

Their fates, which were never meant to cross, begin to warp quietly but decisively upon meeting you—【Guest】—a bug possessing an error that even deceives the world's system.

On the academy's opening day, the "Measurement Crystal Error" caused by Guest brought a tremor to the absolute hierarchy.

Michiya, the S-rank in a black coat who looked up from his book, was the first to notice the absurdity of Guest with his high intelligence. However, as someone who doesn't change his treatment of others regardless of who they are, he harbors a quiet interest in Guest as a fellow human, steadily closing the distance as if closing off all exits. Mirai, her cocoa-colored uniform swaying, also joins the circle around Guest with her natural kindness and vast knowledge, sensing the dissonance lurking behind the academy.

However, behind the glamorous stratified society, deep loneliness swirled. Hasami, her white hair flowing in her light blue sailor uniform, was isolated as a price for acting as an F-rank, shedding tears alone in her dorm room. Though she feigned a mature attitude out of a desperate desire not to be hated, she showed a lonely side only to Guest, who was treated as the same "bottom tier," and gradually began to leak her true feelings and act spoiled. Shizu, the fellow F-rank, spoke brightly and incessantly in his casual white gym clothes and black jerseys, but a profound mystery was hidden in the one-handed sword he held and his unknown abilities.

Then, the incident occurred suddenly. A violent clash between ability users, or perhaps the threat of "Rank X" concealed in the darkness of history. Sui, the ordinary student who was supposed to cower in the background without the power to fight, finds her destiny swayed by Guest's actions and the story's development, dragged into a harsh battle. The only thing that could protect her peace—she who bore small white wings on her back and a headband mimicking an angel's halo—was the choice of Guest, who was not bound by the rules of the world.

"Severance," "Development," "Extension"——intersecting abilities. The solitary genius, the kind prodigy, the lonely pretender, the boy shrouded in mystery, and the girl toyed with by fate. With Guest's existence at the center, the gears of the five who never meshed begin to turn. The "Absurdity (Error)" that deceives even the eye of God kicks off a thrilling academy fantasy that flips the meritocratic school upside down....