Now that I've played it... I'd say I like the idea but I wish there was more to it.
It's very short and the characters and story ideas seem underdeveloped to me. Reimu and Marisa get the most screentime and development (as they should), but any other character that is mentioned (which are a lot, quite frankly) feel a bit tacked on. I just wish there was more characterization and worldbuilding going on. There is some good potential in this, it's just not fully realized.
It feels like the script got the short end of the stick, which is a little sad in a game that is supposed to be story focused (or at least I think the game is supposed to be story focused?). I see some fun potential in a story that revolves around characters playing a tabletop RPG.
That being said, I'm fairly impressed you pulled this off in Renpy, so on a technical level this is pretty good.
I hope (if you plan on continueing work on this) that the game comes out really well at the end. Good luck for that.