Now, and correct me if I'm wrong, the final location in the demo where the first tier is obtained serves as the new hub for the two heroines in their onward adventures. Each tier of sin that is achieved brings the base more in line with the aesthetic of the heroine. As in more coral will grow from the walls, sea glass will tangle from larger jellyfish chandeliers, etc, as she grows. At the end, they make a somber walk back to the ruins of the starting hovel as the music swells where the building has all but collapsed apart from the fireplace, it ingites, and she dives in.
Then Martin Scorsese himself walks out of Beleth's gate and hands you an Oscar.