Murder Murder

In a response to rising crime rates and public demand for stronger legislation, Japan has constructed an experimental site to "recycle" death row inmates... Death matches between murderers! With direct orders from the top, newly transferred Rei Minagawa is brought in to watch over Risa Suou, a fashionable murderer who only goes after criminals! Can a straight-laced cop and a moral murderer make it to the top?!

(Source: MangaDex)