I believe this is an allegory for the union of digital and analog art. This makes sense when you consider the work's unusual method of production (as outlined here ): nababa simultaneously worked on both digital and analog versions, with 6 drafts each for both this post and post #614356. As such, there is both the internal unity of disparate media as seen physically in the boy and the girl, as well as the external penetration of one media by elements that might more properly belong to its opposite.
Some additional themes: - the exclusion of digital art from the category of fine art due to its ease of reproduction, as opposed to the uniqueness of an analog work (the copy of an analog work can never be exact, whereas with a digital work it is exact). - the exclusion of the art of the geek/otaku subculture from the world of fine art in general; this leads to nababa's drawing of a parallel between digital art and the otaku subculture. - in eroge, the use of the subjective viewpoint to remove the barrier between the player and the girl. The irony, as nababa points out, is that the barrier remains fundamentally insuperable: the player inhabits the analog world, the girl the digital. This work also parodies that problem.
Influences: Takashi Murakami, Makoto Aida.
Of course, if you can read Japanese you can skip this crude paraphrase of what Google translate gave me and just read his extensive commentary.
