VITA Sexualis

While delivering a secret weapon to a colleague, Shirou encounters Amane Mao, a young woman with superhuman strength capable of lifting cars. Suddenly, an ERROR—a monstrous entity that devastated Old Tokyo fourteen years prior—reappears and begins a rampage. As Shirou argues with his colleague over whether to deploy the weapon to save civilians, his companion is killed in the chaos. Facing imminent death, Shirou has no choice but to merge with Mao using the secret weapon, combining their powers to destroy the ERROR.