Tokyo Mermaid

Tokyo survived a massive earthquake, and the ruins of it turned into an illegal zone.

Langhao and her sister Mika, a cosplay masochistic young lady, encounter a mysterious cat girl creature. The three people start to travel together and notice the shadow of a mysterious organization. Nonstop erotic survival battle develops in Tokyo set into ruins. What is the true identity of a cat girl? And what is the conspiracy behind the mysterious organization?

[From vndbreview]