From MangaHelpers:
The world is filled with cruel scum, ranging from petty thieves to sociopath maniacs. When a vile low-life inflicts pain and suffering on innocent victims, sometimes their anger becomes overwhelming. Whether their damage stems from romance, finance, reputation, or even death, these victims feel trapped in their own skins and lives. Those victims who can't stand it anymore call for the mysterious woman Houjou Shiori, owner of Uramiya, the "Revenge Shop". Uramiya specializes in executing revenge schemes. The vengeance their customers request on their bitterly resented enemies could range from financially destroying them, to smearing their social reputation, to even taking their lives. As long as you pay a fair price, the Uramiya will guarantee you get the revenge you deserve.