He's probably a fallen angel or a half breed. It makes sense since he said himself that in Hell he was an outcast and everyone treated him badly, the only person treating him well being a landlady. Maybe she has more to do with the plot, but that's getting to some stretched conspiracy shit
I've been thinking this for a while, but what if the final memory isn't the final confession? What if it was when he went back in time and met young Umi? I mean, the final piece is toward the beginning of the memory puzzle board. I think it could make sense. A final trial from God to see if...