Moon Rabbit Reisen
Is that why チルノ is spelled C-I-R-N-O instead of C-H-I-R-U-N-O?
Not really. I'd rather say
Cirno is spelled チルノ, and not the other way around.
You see, there a bunch of names used in Touhou that ZUN fully intended to be understood as European borrowings (he himself said he wanted to create a game with a Western-feeling atmosphere). For example, Alice, Remilia, Patchouli. Since he was and
is producing games for a Japanese-speaking public, he did his best to convert those names to katakana so his public could read them more easily, even if that implied distorting the original name in cases in which the original names have either unexistant syllables in Japanese (like
ti for
Letty) or foreign sounds (like the
L in
Alice)... Well,
Cirno is one of those names, hence why it's never written "Chiruno" in the Roman alphabet.
An easy way to see which names are intended to be European and which ones are not is to look up at the characters' portraits in PMiSS. Every Touhoe there has her name written next to her; some names are written with the Roman alphabet while others are not.
Fun fact: In real history, a bunch of European names were suddenly started to being used in feudal Japan by the chronological time the Great Hakurei Border was finished.
Marisa was one of those names, even though it's of Spanish origin. Since it complies with Japanese phonological constraints (its three syllables are existant in the Japanese language), it was eventually given its own kanji.
Edit: All I've said accounts for how the names are
written. As for how they're
pronounced in speaking... I guess we'll have to either look up how they're pronounced on their supposed original languages (Alice is English, Marisa is Spanish, Remilia sounds Italian,
et c.) or wait for an official anime or non-instrumental song to know it.
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