"Hayato Ibuki, a journalist for an occult magazine, was investigating the mysterious suicides that were taking place in Shinjuku station. During his investigations, a black shadow pushes Hayato onto the tracks. A beautiful, mysterious girl, Balucia, saved Hayato at the last moment and gave him a large case... And thus, Hayato's new life began.

Inside the case is the demon gun, Gangour, which is a tool that can capture and use demons. Hayato uses its power to turn demons into allies.

With the Gangour in hand, and accompanied by the self-proclaimed angel Lua, the supposed chosen one, Hayato, travels all over the country to investigate mysteries and search for that beautiful mystery woman. And while he's at it, he gets caught between the ambitions of the dark rulers and the expectations of the angels..."