This visual novel was great! I can definitely see the CHARON inspiration. Here's the first part of my playthrough for anyone interested (Ichigo just has some strawberry jam on his face in the thumbnail, don't worry about it):
The UI design is competent, the artstyle looks good, and while I had a few issues with the grammar (but only because I'm annoyingly pedantic) the writing hit the right parts for me. Though the themes might not be for everyone, I'm very biased in that I love these types of stories.
My only gripes would be that I felt one of the endings was too "nice" for the protagonist and the way Yuzuki's backstory was told didn't feel like it fit with the rest of the pacing in the game, but these are just my opinions.
Otherwise, Sweetest Valentine was an enjoyable experience and I wish the developer all the best for their potential next project!