This is the Guns Girl Z: Fire Moth story recreated in the RepliCant engine, a Visual Novel engine written by Amaryllisworks. That means you can read the whole Guns GirlZ: Fire Moth story on your own using this software, since the game is no longer available in English.

The VN engine is source-available and can be used by anyone as long as you are not intending to make profits off it. You are free to use it for your own things.