it was originally in the Lugunican characters, and the source translated it to hiragana.
[Rem: Thank you very much for the birthday party. I’m very happy that you would celebrate Rem and nee-sama’s birth. I’m sure lots of different things will happen in the future, but I hope we can talk like this again next year. Let’s have a good year.
- From everyone’s Rem, just for today]
(Note: The close is probably contrasting with her letter in episode 14, which she closed with “From your Rem”)