In the year 3990, the immortal Oldna Poseidal rules Pentagona, a war-torn solar system of five planets. Daba Myroad is a survivor of the Yaman Clan, just one of numerous native societies nearly wiped out by the tyrant. Living on the remote planet Koam with his friend Mirao Kyao, Daba possesses L-Gaim, a humanoid mecha known commonly as a "Heavy Metal" and the last known relic of the Yaman Clan. The pair befriend Fann...