To be absolutely frank,I dont think the writer is up to the task.
The writing is already all over the place(especially for the youngest)and adding two more characters who´s initial plans very obviously flew out of the window isnt exactly going to help.
I have to respectfully disagree with you on this one. Every story of every kind has characters that are not "main" characters that still contribute to the story, even in small ways. The number of characters that BlueCat has been able to develop, some of them a little, and some of them quite a bit, in just a 7 day play span is nothing short of phenomenal.
As a fellow game developer I also appreciate the nuanced things that take a lot of development time but which add humour to the story, like changing the "names" of the characters as their characters emerge, like the scene in the mall where Strange Girl > Strange Girl with Eyepatch > Triggered Aggressive Eyepatch Girl > Nao. While it seems simple, it involves touching four different pieces of code and it is done in this scene and other scenes where it injects considerable humor into the story.
And as far as the story being "all over the place" I have to disagree again with you on this one. While the MC may be all over the place in that he's pursuing multiple women, once each storyline is established each one of them progress in a consistent manner -- sometimes an unpredictable manner -- but still consistent.
Actually some of the writing is just short of brilliant. I just rewatched the scene where the MC almost rapes Saki and the dialogue that the writer created for Saki is pure genius. The MC's reaction is totally understandable, where he's freaked out and wants to get out of there, but what Saki says reveals her internal strength as a woman and daughter, as well as her deep love for her father, and her willingness to fight to keep the close relationship they have developed.