Makoto Nakane once served as Metal Woman of Guardian Force, a celebrated heroine. Now retired from heroics, she lives a quiet life with her family. But her peaceful existence is shattered by an unexpected event. Her former superior, Commander Moriyama, receives a threatening message from Galo, a ruthless executioner working for a criminal organization. Galo has taken her comrades hostage and demands that Makoto come alone to save them. For reasons unknown, Makoto has been specifically targeted. Venturing alone to the enemy's hideout, she faces relentless torture through water and powerful currents. As memories of past battles resurface, she is thrust once again into combat. Can she reclaim the happiness she once knew?