Alright, I've played through most of the demo (just need to do Shizune's mini-route) and am finally ready to give my uber long post of feedbackness. I don't know if the devs will actually read this far into this topic, but I hope...
But first, I REALLY like how skip mode automatically deactivates when you reach unread text.
First off, Yuuko seems to be is a slightly different art style. This is not really noticable when she's the only one on-screen, but when she's beside Lilly in the library, you could see how Yuuko didn't have dark outlines around her hands and stuff like Lilly did. Yuuko also seems to have a more overall style of gradients and "fading color tones" much more so than other characters (such as, yet again, Lilly)
Secondly, some of the CGs seem a little TOO photo-like, such Hisao's bedroom and the bathroom. A good majority are fine though, like the rooftop.
The image of the night sky (the one for fireworks and seen in "Mind your step") has very noticable colorbanding. I realize KS's art style doesn't have perfectly smooth gradients all the time, but this is one time where it just looks bad.
In the background image for the scene where you first see Lilly in "Mind your step", you can see a road sign about 2/3 down and 3/4 to the right. Said roadsign is on the right side of the road, but japan drives on the left. May I recomment mirroring the background image? Make sure you mirror the night version too, when you're heading back to the school.
Typo in "Sip (part 2)"
Given the large number of accomodations and facilities that the school offers, many of them might simply not see any point it venturing outside, let alone people such as Hanako and Kenji.
should be "in" instead
In the background image for Lilly's stall for the festival, there's clearly a "Coca Cola" logo on the umbrella. Speaking of brand names, the convenience store's katakana name still says seven eleven (well, seburen erebun or whatever it says)
Muto barely has any different character images, giving a very monotone personality. Or is this intentional?
When loading a game, it says "Are you sure you want to discard your progress?". This is a bit confusing since that makes it sound like you accidentally clicked the X to delete a save. Something like "Discard current progress and load save state?" may be better.
In the Jukebox, when using a gamepad or arrow keys, you cannot highlight and select ">> Return" in ways normally expected. The ONLY way to do this is to highlight a song on the list, and go right. You cannot go right from stop, nor go down from the scroll buttons.
At points where Rin moves her head from side to side quickly, the on-screen animation really just looks like she's a robot spazzing out, probably from the lack of the fade-transition normally used on image changes. With the fade-transition, it may look more like a motion blur effect from motion and moving, therefore looking better.
Rin and Emi's name colors really should be swapped...
Any plans on using Ren'Py 7 in the future? The OpenGL hardware acceleration could be very useful for all the fancy effects.
There's also some sort of inconsistancy between two branches that I forgot to put in here before I deleted the save file... I'll see if I can find it again at some point. (it's not the one already posted about the boy in the art club)