Don't take this too seriously
Random Theory Time: The main cast are actually mostly Western people that got Otaku-fied because whoever created this world was an Otaku. (I think some people never existed while others did, but that's beside the point)
The reason Amy:
Is named "Amy" is because "Amy" is Ami's real name. Before this version of the world was created, she was possibly Sensei's niece, but was named Amy. I doubt she actually had that red hair, but she maybe did have twintails due to being an otaku herself.
It's possible that everyone's name is actually fake. It's why Pareidolia noted they know Yumi by another name:
Virtually every alliteration name is likely a lie, including Akira Arakawa. Even Nozomu which means Hope and Sekai which means World are made up names for people that may or may not have existed at some point.
Niki being some kind of childhood ex turned Idol is also likely BS:
She maybe did exist, but she was likely a non-pink haired friend who was named Nicole. Probably had Niki as her nickname due to being an otaku as well, since she'd watch Anime with Sensei. Something he'd also do with Amy.
In fact, I doubt anyone with naturally odd hair was ever real. Like how Noriko implies her Pink Hair is natural:
Niki might be the one exception, and I can see her dying her hair if she was real.
There's also how certain characters have western names like John, Todd, Matthew, Gary, Geoffrey, etc. Possibly even the Shapeshifter if her name is Daisy.
Overall: The reason anything might seem westernized in this game, is because this is actually a world made by an Otaku, not an actual person in Japan. Just no one knows that in universe, even though they may feel it. Hence stuff like Rin mentioning middle names:
and maybe where she's actually from.
