I'll write down my thoughts as I play!
First of all, a very cute main menu, looks so stylish ^^ Overall, I love the visual design. And the fact I got to type in my name :D (Got to custom pronouns too now, that's so considerate ^^)
I got so invested in the story I forgot to write here xD I love that there is a mystery, and all LIs are so interesting! +_+ Erinna is cute too!^^ And I think the text is very well written :)
I didn't mind small bits in french, thankfully I had french in school lol. But yeah obv it'll need to be fixed for a full English release <3 (Though it kinda made atmosphere of the game more interesting to me...:D)
Lastly, I wasn't quick enough to read the notice at the end of the demo! It disappeared by itself :')
Overall the game seems super cool, I loved it and will definitely try it out again after some updates/full release! <3