Thank you for your support and interest!
To answer your question, i think "BRILLIANT BLUE" is not too short but also not too long. And the VN will be non-linear with choices inside it!
If you are referring to the character "Fellten Hwolfe", don't worry, he will still be there with the same name but with a minor redesign and new sprite(goes with our hare protagonist, Emil too)!
If you are referring to the VN title, yes, "FELLTEN" will be changed into "REPENTIR" for a brand new theme and storyline.
For the plot, yeah, there will be a bit of changes regarding to both Fellten and Emil. Especially on the prologue (beginning of the VN).
Once again, thank you for the questions!
I'll do my best!