We can call this "adult Mokou" despite the obvious complications of doing so, but I think the real issue is that Mokou is one of those weird Touhou characters that doesn't seem to have a completely "accepted" set of proportions. Similar to how Patchoulli can be thin as a rail, super-busty, or plump, depending on the artist.
Of course, with a series like Touhou where a lot of the work isn't really canon, there's going to be artists who change a character's characteristics just to experiment or because they just felt like drawing someone in an unusual form. But a lot of characters, like Reimu, seem to remain pretty consistent between artists (after you account for stylistic differences, of course).
