Twin Souls is a game about a stealthy assassin spirit brought to life by an imprisoned noble girl, and tasked with rescuing her from a tricky predicament. You are this spirit, the particularly killy Aragami, and because you're basically made of shadows you can do nifty stuff like summon shadow dragons and teleport about. By the looks of it, it's Tenchu mashed together with Dishonored and maybe a bit of Mark of the Ninja—'something to keep an eye on', in other words.
A new E3 trailer, below, shows a few of Aragami's shady powers in action, and reveals the game's release date: Spring 2016. (There are other seasons to release things in, games industry.)