Porn Game: Tokyo Necro by Nitroplus jap

The protagonists, Nagaoka Souun and Kibanohara Ethica, are young "Private Special Living Dead Stalkers". By practicing a special kind of martial art called "Close Quarter Armed Martial Arts", both of them have achieved great heights in their career.
Out on a mission one day, Souun becomes involved in a fierce battle and meets a young girl. Remembering nothing but her name, "Hougyou Ilia", she has become the target of a mysterious group of necromancers.
The ice-cold Tokyo of gunpowder smoke, living dead, crime and cybernetics. Now begins the battle of the living dead stalkers and the heroine with their lives at stake.

Tokyo Necro by Nitroplus jap game preview

online.