Essentially, what the “Twilight Machine” is, is the explosion and prevalence of the Teen Paranormal Romance genre within the wake of the initial book’s publication. All these books shall feature similar (if not identical) elements:
1. First-person narrative from the perspective of the female protagonist
2. Life (or “plot”) begins at man — whether the meeting is first positive or negative, but especially once it’s positive
3. The plot is primarily (aka: first and foremost) a romance; everything else is secondary to serve the romance
4. There is a paranormal/supernatural gimmick, whether it be vampires, werewolves, aliens, fairies, fallen angels, et al.
5. The female protagonist is usually introverted, almost cripplingly self-conscious, and/or such a broad, under-developed character, that she serves primarily for the reader to be easily able to project themselves into her place
How does Ink come into play here?
Ink benefits from being able to strike away #4 and #5 from this list; arguably there is a plot going on from before #2, but it doesn’t really get rolling until Katie meets and begins interacting with Tomohiro. The plot, while a romance, is more about the kami and the dangerous war of sorts that is occurring amidst them and instead of serving the romance, the romance serves this plot. Finally, Katie is actually a character — nothing remarkable like, say, Hermione or any other great female leads, but she’s more than just a hollow shell into whom one can easily inject their own person. I give it that, at least.