kimonomiko said:
If anything, I could maybe see monomi -> usami, but not the other way around.
Usami exists for less than 30 minutes before being turned into Monomi, and she stays that way for the remaining 30-60 hours of the game. Is Usami technically her true, original form? Yes. Should we ignore the context of the entire game itself and tag her as such? No.
As I mentioned before, there is a very good reason midna_(true) implies midna rather than the other way round. They even have about the same amount of posts as Usami and Monomi - if this BUR is rejected, we'd just be picking and choosing which of these such scenarios to imply based on a whim.
They are the same character with different names, but each form is drawn separately frequently enough that I think it's useful not to muddle them together. Kind of like how sailor moon and tsukino usagi don't imply each other.
Superhero and magical girl tagging are outliers that are handled in a number of different ways depending on the media in question, and should not be looked to for inspiration when discussing alternate form implications.
If a character called Daniel Booru occasionally decided to slap paint on half his body, wear a diaper, and demand to be called "Diaper Dan", then we'd have a diaper_dan tag which would imply daniel_booru. We don't consider an alternate costume/form to be a different character just because the character's name is different; Usami and Monomi are no exception. The only difference is that Usami should imply Monomi, because as I mentioned, Monomi is objectively the "main" form, even if it's not her true form.