Hello and welcome to Feedback Quest 9! My name is Hythrain, and I'm one of the hosts for this lovely event! I'm also one of the streamers, so both the game and this feedback are being done live! If you want to see the see the VOD, let me know and I'll link you to it when it's uploaded to YouTube!
So this is, by far, one of the best visual novels I've seen in these events. Whereas many of them use stock images for the background, everything here is made for this game specifically. This gives it a lot of value in my book. I didn't reach the end of the demo due to time constraints (lots of games to cover), but I think I have enough feedback for you. Before I get into it, I should note that my typical approach for visual novels is to focus on the writing; ensure sentences are well written without typos or mistakes, and to ensure the logic of the story makes sense. Normally, this leads to me doing a lot of quoting of lines to rewrite them. However, everything I saw was well written and I didn't need to do this. The most I saw was that some lines had extra commas when they didn't need them, but even then they're not a big deal. This means I primarily looked at the overall logic for this.
Before I get into that, there are a few notes I want to start with.
First, I'd recommend not making the game be in full screen. Renpy has issues with full screen, making it that one's mouse cursor doesn't show up. In order to play the game, I had to force it off of full screen.
Second, it'd be a better idea to let the player progress the starting screens so that they can fully read the warnings in time. Even when I was reading them quickly from the moment they appeared, I couldn't finish in time before it's transition to the next screen.
Third, I noticed that this game doesn't have a Back button unlike most visual novels. I assume this is so players can't change their choices, which I think is fine. That said, I still think that you should have a Back button that lets players see scenes again and just put in programming that forces them to keep the choices they made in the playthrough. That way, they can go back to previous scenes and rewatch them to see if they missed any details. In a similar vein, I'd recommend making the text boxes while viewing the History much smaller. They're pretty huge right now.
And lastly for my starting notes, I think you should remove your logo from before the warnings as you're also showing it after the warnings. It'd make sense to give the warnings, then show your logo as you go into the intro (As an aside, I also hope that song is copyright free. @_@).
With that said, let's get into the logic issues I picked up on.
First, the start was awkward. It doesn't introduce us at all in some way to the character and instead just throws us a line beginning with "That evening" as if we're in the middle of a story rather than at the beginning. While I get you can't give the person a name, I do think it'd be better to open in a different way. Something that feels more organic to the start of a story.
When you listed the Seven Deadly Sins, you listed Despondency instead of Sloth. I know that when the list of Deadly Sins was reduced from 9 to 8, Despondency was one of them. I'm guessing you did this because writing one of the boys as representing Despondency is easier than Sloth. I also assume that Dan is suppose to be Despondency, but I could be wrong. I'll be working with the assumption that he is, though. With that said, since you're explicitly using 7 I feel like it's better to keep to what people are used to and make this Sloth. Given that Dan would be the one to question here, I feel like he could still represent Sloth with the more laid back nature he showcases in the beginning.
Next... how did the main character know that the yellow guy was named Ernie? She's the first person to say his name, but she shouldn't know that yet.
And for my last note before I had to stop playing... why isn't Ray shirtless right after Ernie leaves? Was he not shirtless in the previous scene from wanting to take a shower? I feel like he should still be shirtless. Also because having a clearer image of him being shirtless would be hot. :3 You could then maybe specify that he's putting his shirt on when he steps aside.
There's also one last thing I'd like to cover. I noticed in the warnings that this says it's 18+ and contains sexual content. However, streamers can't show this sort of content. We can get banned from platforms for it. Between this and the fact that this event is more intended as being for all ages, I'd like to recommend adding a PG-13 version that removes any explicit content.
That's all I have! I legit can't wait for more of this. I'll probably try to play the entire demo at some point in the future (especially if you add a PG-13 mode).