[Kiwami]

So, I think our Sento (Build) is Takumi Katsuragi with Taro Satou's face who had his mind wiped by Faust. The dead body is Taro Satou with Katsuragi's face.

The cafe owner is Blood Stalk. He created Faust alongside Katsuragi, maybe for a good cause (or at least not all-out war), but things went downhill after Night Rogue took over. The "Faust doesn't belong to you!"-quote from Blood Stalk might be telling us something.

It's a bit convoluted but I wouldn't put it beyond this show to pull it off.