學園都市製作的宇宙升降機「安迪米昂」完成在即的某一天，上条當麻和茵蒂克絲與擁有「奇蹟」的歌聲的少女鳴護艾莉紗相遇了，茵蒂克絲與艾莉紗兩人因為「旺盛的食慾」這樣謎一般的羈絆而意氣相合起來，就在三人享受放學後的愉快時光之時，帶著魔術師的史提爾突然發動了襲擊。而本次襲擊的目標正是艾莉紗。為何身為科學世界的艾莉紗會被魔法世界的人追擊？因為受到了魔法世界的強烈攻勢，學園都市一側的莎特奧拉率領著秩序維護部隊開始了行動。上条與茵蒂克絲還有艾莉紗他們因被捲入這樣的狀況而極度混亂迷茫，史提爾對他們這樣說道：「那裡的她，將會引發魔法世界跟科學世界之間的戰爭」。 在科學與魔術魔法交匯之時，以「安迪米昂」為舞台的故事開始展開。

Bonus animation featuring Index-tan included with the BD special edition of the Toaru Majutsu no Index: Endymion no Kiseki movie.

In Toaru Kagaku no Railgun T Mikoto Misaka and her friends prepare for the Daihasei Festival, a seven-day sports competition between different Esper schools, which, of course, also include the Tokiwadai middle school. Misaka and all other students of Tokiwadai are highly motivated and ready to do their best in the upcoming competition. However, all the fun ends, when another dark secret of the Academy City of Science and Technology is uncovered.