AragoAR∀GO ; AR∀GO -ロンドン市警特殊犯罪捜査官- ; AR∀GO - London Shikei Tokushu Hanzai Sousakan ; Arago - 伦敦市警特殊犯罪搜查官 ; Arago - 魔都伦敦特殊犯罪搜查官 ; Arago - 魔都特殊犯罪侦查官 ; Arago - London Shikei Tokushu Hanzai Sōsakan ; Arago - London Shikei Tokushu Hanzai Sousakan

The story centers around two twins, Arago and Ewan, whose parents were slaughtered by monsters. Years later, the vengeful Arago crosses paths with Ewan, who has since become a police officer, just as blood begins to flow again in the streets of London.