Oh, thank you so much! That makes me really happy ^^
Only Vuu and Rose can reach R5 in the demo, the rest can only reach R4. Every character will be playable in the next demo (which should be out near the end of 2021), and they will all be able to reach R5 then. There will even be a R6 in the final game, but it's going to take a few more years after the next demo.
Thank you again! I'll do my best ^^