The young Eric brothers missed their deceased mother so much that they violated the biggest taboo in alchemy and performed human transmutation. However, the transmutation failed. The elder brother Edward lost his left leg and right arm, and the younger brother Alphonse lost his body and could only attach his soul to a suit of armor. In order to atone for their sins and get back everything they lost, the two brothers embarked on a journey to find the legendary "Philosopher's Stone". A few years later, a national alchemist whose right arm and left leg were replaced by "mechanical armor" appeared in front of people. He was called "Fullmetal Alchemist".