本当は日本育ちで日本語話者だが、キャラ付けの為にわざと外国人風の日本語で話している。

空ちゃん描いてて楽しかったので、こっちの子も描きました…！

https://fantia.jp/posts/2552829
こちらでやり取りを書いています～！ （無料記事）

She really was raised in Japan, and is a Japanese speaker, but she goes out of her way to speak with a foreign accent for the sake of her character.

I had a lot of fun "drawing Sora-chan":[/posts/7210120], so I went and drew another girl...!

https://fantia.jp/posts/2552829
I've written a longer exchange here~! (it's a free article)