It is a fun game and I would rate it 4/5 stars generally. Maybe a tad below that.
First, the positive. The art style is unique and interesting and the characters are the same. Their design is a mix of aninmals and the like, giving it a nice fantasy vibe. The atmosphere of the small village is mysterious and interesting, albeit the houses are pretty much all the same. The door window is a good mechanic though, as the soft pink glow shows where you can enter. The grass moves in a rustling effect of sorts and the trees let you see your silhouette while behind them. Nice effects that enhance the experience. A good detail, albeit there are details missing in some parts.
This brings us to the bad. Or let's just say critique points that would be lovely if they were improved upon. The missing details I am talking about are the sex scenes. Lovely art, albeit very very little of it. They do not really illustrate scenes that well, with a body pressing into a tail or Mona cumming into lovely Yu's mouth without being shown. There is also text about slime from our lovely snail weirdo Mona in her shell, without any hint of it being seen in the pictures, which is a big pity. Give me my proper snail action, dammit! xD The worm-tentacle scene isn't illustrated yet and I have yet to see what happens with the egg after I wait for a few days. I sincerely hope this is a work-in-progress game, but am unsure about it, since it might have been a year since I played it last time and back then, there was no worm/tentacle scene in there too.
The walking mechanic is a bit annoying. Not to say the plug is a bad idea. Quite the opposite in fact. Yu only is squirting so fast that its effects are minimal. Girl should hold out longer if you ask me! xD Her enduring it longer would help with it being more useful as well as possibly an option to keep the plug in. I gave up using the plug very early because it wasn't that practical. Another important mechanic is the whole searching of trash cans and the like. I didn't know I could do it and only stumbled on it by pure accident. Having the E illustration show when one is near them would be best to solve that problem. It is problematic if the player has no idea that trash cans can be searched. The last stretch of the game with the worm/tentacle is harder to find and could use some hints from the mayor. He is definitely underused and could serve to give more hints to several things. For example, who the coin purse belongs to or what to do with snail slime vials! xD (Looking for advice on that one.)
Anyway, that is my review about the game. Lots of good stuff, but also some things that could definitely use tweaking. The lack of art in scenes is the biggest problem with it to note it down once again. In any case a solid game that I recommend regardless and I respect the creativity of the character designs and the design in general. =3
Edit: I am wondering why one cannot rest at home to pass time as well. It is a bit frustrating to always have to do the Marionette minigame to be able to return home. Not sure if it is necessary to be blocked to go home. For now it looks more like a bit of a hindrance. Just as another critique point.