The occult group, Shiromorishuua, dispatches a massive monster to Tokyo, prompting retaliation from ASY, a peace-keeping organization in Japan, who unleash their Gousen (metal fairy). The Gousen succeeds in destroying the beast by forcing it into the open ocean, but a surprise attack comes shortly after. A luminous girl named Rouran, suspended in midair, launches a beam of light at ASY. Despite her ability to transform into an avenging angel in the presence of Gousen or Kyoushi, Rouran has no knowledge of her identity or origins. Meanwhile, Tetsuya ensures her safety in Tokyo Arcadia, a community of expatriates and rebels, as she contemplates her perplexing existence.