I've been sitting on this idea for a while. I remember mentioning it somewhere. It seemed like such an odd idea I'd have to do it. I had a different love interest in mind for Lucy as one point, but this seems more fun. I didn't create Tyrone for this reason though.
I'm not sure this reasoning is important enough to cover in the story, but I assume neither Lucy or Tyrone can use something to change their size (magic or whatever) because of their cybernetics. Usually when that kind of thing happens, it doesn't alter anything that isn't natural.
I also corrected a typo mentioned on Twitter on page 192, and I still have to correct the steep rank on page 193, and I think three small art mistakes in the last chapter.