Menacing in appearance but gentle at heart, second year high school student Ryuuji forms an unlikely friendship with classmate Taiga, a tiny girl with a sharp tongue and a tough attitude.

时代背景设定在世界变动率为“1.048596%”的2019年。在这样一个机器人已经普遍实用化的未来，种子岛中央高校的“机器人研究部”正面临废部危机，而仅有的两名部员之一——八汐海翔就算面临着这样的情况，仍旧对“机器人研究部”感到兴趣盎然，并且依旧热衷于机器人格斗游戏。而另一位一根筋的废材部长瀬乃宮秋穂为了避免被废部，正在以“完成巨型机器人”为目标奋斗着。然而某天，海翔发现了一份名为“君岛报告”的A.R.笔记。在这份笔记里面，记录着名为君岛安科的人将会把整个世界都卷进来的大阴谋。

Disregard for alchemy’s laws ripped half of Edward Elric’s limbs from his body and left his brother Alphonse’s soul clinging to a suit of armor. To restore what was lost, the brothers seek the Philosopher’s Stone. Enemies and allies – the corrupt military, the Homunculi, and foreign alchemists – will alter the Elric brothers course, but their purpose will remain unchanged and their bond unbreakable.