Look, I don’t have a lot of direct experience with the military, but I do have a pretty good deal of first-hand experience with Midshipmen, both at Annapolis and in ROTC. I can’t speak to how the Marines deal with JOs or officer candidates, but I know for certain that Midshipmen with pretensions of being more important than they really are tend to get ripped apart, by more senior Mids, their actual officers in the chain of command, and by SNCOs. A Midshipman who referred to himself as an Ensign would be considered to have such pretensions, and he wouldn’t be referred to as a “Butter-bar” because he’s not, he’s a Midshipman. In fact, they aren’t even commissioned officers. The rank of Midshipman, all classes, falls somewhere between WO-1 (even though there are no longer any WO-1s) and CWO-2. And linguistically speaking, I cannot fathom a Shoi Kohosei in the days of the IJN referring to himself or being referred to as a Shoi; that would be a gross exaggeration of the candidate’s social position, which runs totally counter to some pretty fundamental cultural mores in Japan.
Of course, this is ultimately Wes’s decision and he thinks referring to Shoi Kohosei as Shoi is fine, so go for it. But speaking from a real-world, non-SARP perspective, that wouldn’t be the case.