とある科学の一方通行〈アクセラレータ〉

東京西部に位置する巨大な『学園都市』。総人口230万人を数え、その約８割を学生が占めるこの都市では、超能力開発のための特殊なカリキュラムが実施され、学生たちの能力は『無能力レベル０』から『超能力レベル５』までの六段階で評価されていた。そんな学園都市で、能力者たちの頂点に君臨する最強の能力者・アクセラレータ。 ７人しかいない『超能力者』の中でも、飛び抜けた能力を誇る第一位は、その力ゆえに殺伐とした日常を送っていた。繰り返される常軌を逸した『実験』と、絶対的な力を求めた末に経験した敗北。その先に待っていた、とある少女――ラストオーダーとの出会いによって、運命が大きく変わることになる。

The espers of Academy City are classified into six levels, where "Level 0" lacks power while "Level 5" possesses an overwhelming amount. Of the several million espers residing in Academy City, only seven of them have attained Level 5, and ranked highest among them is the one known as Accelerator.

Toaru Kagaku no Accelerator focuses on the strongest Level 5 after he protects the cheerful Last Order at the price of much of his power. Recovering at the hospital, Accelerator has led a relatively quiet life until he ends up saving the life of Esther Rosenthal, a mysterious girl carrying a photo of Last Order. Unfortunately, Accelerator now finds himself dragged into a new conflict in the form of a sinister organization called Disciplinary Action which plots to use Last Order for a dangerous mission. Now that they have set their plan into motion and are in pursuit of the young girl, it's up to the world's most powerful esper and his newfound companion to protect Last Order and defend Academy City in the process.

[Written by MAL Rewrite]