What's the Subject in: 'And up here in the corner is me'

If two people are looking at a photo, and one of them pointing out the different people says:

And up here in the corner is me.

... what is the Subject of the sentence?

The phrase up here in the corner feels like a Locative Complement. It is tempting to see this as a case of subject-dependent inversion like On the corner is a cafe. However, the NP me has accusative case and the verb is third person singular. The sentence isn't:

• *And up here in the corner am me.

Also, if and only if, 'me' is not the Subject, what type of use of the verb BE is this? If me is an internal Complement of the verb, then this doesn't seem to be a specifying, ascriptive or locative use in the normal sense (me is not a description of up in the corner, neither is it a location. And the sentence does not mean "up in the corner = me").

And if, and only if, me is the Subject, why is me acceptable instead of I? Does me invariably take third person singular agreement of the verb?