For some reason, I have a hunch that there's a higher chance of it being a newly introduced character rather than the mc's naked torso.
I painstakingly tried to find a mach as well comparing it side by side to my decrypted image files, to no avail.
Looking at the bottom panel of the Weekly Report the figure on the right doesn't seem to possess the curved flaring hips of any of the sirens, not even slim ones like Alia, Emiliy and Sofia, which is why I thought it might be the MC himself as a logical alternative.
I never considered a wild card like a new character being thrown in to the mix.
If the bottom panel doesn't involve a Booty Call it must be a scene integral to the story and I'm wondering whether one of the three new scenes, mentioned in the Weekly Report, might involve one of the women paying a visit to Henry's home spontaneously, without his call, which would be a first when you think about it. Apart from Diana every visitor admitted to the MC's home has involved a Booty Call. Now, as I remember it, a few episodes back, the MC invited Janet to visit his house at some point, to have a look around and see what he'd done with the place, and she accepted. So maybe one of the forthcoming scenes involves Janet walking/driving to the MC's home to check it out and converse with him privately. (Looking at the top panel in the Weekly Report I can't work out exactly where Janet is based on what little I can see of the background behind her. I think she's at home, actually, based on the open plan look and arch behind her.) Also, as I remember it, Kaley once called at his home, off her own bat after the pool party, when he was out, so I suppose that conceivably the same thing could be said of her; Kaley is the only girl who has ever called at the MC's house to see him, of her own initiative, without a Booty Call being involved.
I'm just spinning my wheels here...
Since what happens in Cape Vedra is determined by the imagination of NLT rather than physical processes governed by neat and tidy natural laws it's impossible to calculate or predict anything at all really! All we know is that, probably, Janet, Kaley and Diana will be putting in appearances although I'm not 100% sure of that! We will just have to remain tortured and in agony until tomorrow when everything will be revealed.
If the Patreon servers go belly up and crash again tomorrow the lost and despairing amongst us will be jumping off the ledges of high buildings en masse!