I have little experience with light novel games. The closest game to the genre that I've played would be the Ace Attorney series. I'm know nothing about Ren'Py, so I can't tell how much is out-of-the-box, and what is custom-made. From my perspective, the game plays fine, and is pleasant to navigate through. 

The story was intriguing, and I like the attempt at introducing branching paths. However, each day felt like an abridged version of what it was supposed to be. This felt like it limited the impact whenever I made a choice.  

For example, the first day is about the main character (MC) meeting the other characters, with Zombie being important. Regardless of how unfriendly I was towards Zombie, the plot would force Zombie to be on good terms with me. This is due to the events of day two resulting in learning about a curse in Zombies house, which is needed to keep the plot of days 3 and 4 coherent. Beyond the changes in dialogue, it didn't feel like the choices I made had an impact on the story. 

The first two days could have been longer so that the story setting could be expanded on and allow for actual consequences. For example: 

1. day one would have be an opportunity for the MC to explore the school grounds before meeting the other characters, and potentially introduce some subtle hints about the curse. 
   1. However, taking your time and exploring would result in being scolded for being late to class and other characters acquiring a low opinion of MC. 
   2. Alternatively, going straight to the class wouldn't result in the scolding dialogue. The trade-off is between character relations and in-game character knowledge. 
2. during the initial meeting with Zombie, you could be friendly and that would result in day two playing out as normal i.e. going to Zombie's house and learning about the curse, possibly through the information gleaned from day one. 
   1. However, being unfriendly to Zombie would result in a slightly different scenario in day two where you need to put in more effort to befriend Zombie. 
      1. Success would cause the normal day two scenario to play out. 
      2. Failure would result in the MC not confirming that the curse is legitimate and then they die some time later during the school year due to an "unknown" cause.

By expanding the first two days, there is more room for potential branching to the story, and a consequence is included for not following the story's intended path. Mind you, this is under the assumption that the story is intended to have supernatural themes as signalled by use of zombie and feline character designs.

Overall, it has an interesting premise, but the story limits how complex it can become.