Not only do you not really miss anything from skipping the prologue, I actively recommend that you do so for your sanity. This is from the game's own readme:
The prologue of this work is a prequel to the main chapter, which consists of seven chapters.
There are almost no flags or obtainable items that are exclusive to the prologue,
so if you have already confirmed the contents in the trial version, etc., you can skip it without any problems.
We recommend that you play through it once to better understand the story,
so we have used a hidden command-like method to skip the prologue.
You can start from the main chapter without any problems.
You can also use the skip function if you want to enjoy the RPG parts and H-scenes quickly.
***How to skip the prologue***
On the prologue selection screen (the screen where you select the chibi character and start the prologue), you can select the main chapter by inputting the following in the order:
・In the Snow Country chapter, press the ↑ key twice
・In the Beach chapter, press the ↑ key once
・In the Eastern Country chapter, press the ↑ key once
You will hear a small sound effect when you input something or if your input fails, so use this as a guide.
(If you don't enter your answers slowly, the game may miss a decision.)
***Please note***
Once you enter your answers, you will no longer be able to select the prologue chapter.
Please note that you can still enter your answers even if you have cleared some of the prologue chapters.
Played a ton of the JPN version. I'm also biased towards this circle's work, probably because I like their character designs, art style, and the circle's overarching world that's used in multiple games. If you don't know, it's one where the usual run-of-the-mill monsters are ecologically sexual predators that spare and reproduce with women but kill men, meaning adventurers are almost all exclusively women. On top of that, these female adventurers simply accept that sexual stuff and rape are the norm in their job, though they still all react differently to it (some still hate it, some are apathetic, some see it as a perk).
This game so far might well be my favorite from them, though it's still not perfect. The prologue introduces way too many of the characters you will randomly collect throughout the course of the main game and serve as side stories splitting off the actual heroine's own prologue into parts.
The problem is that the ero scenes here are sparse (one per side story usually, often softcore, with one for the MC when her prologue advances). They're also SLOW and filler-y. None of the side stories are interesting either. You will meet those characters eventually anyway, and their own issues hinted in the side stories are regulated to quests with little additional writing (i.e. guess I have to find and fight the rest of these ice demons, who are also just sitting in the world with no narrative prompting).
Basically, don't think too much about the prologue stories, and they are very skippable if you want to rush them. Bright side of this is that the cast is huge, with a wide variety of body types, and many of them get at least one of their own ero scene chains. This is similar to how Nightmare Girls worked if you played that, except that one character gets the lion's share of scene event chains this time (the MC).
Content varies wildly, from bestiality to tentacles, to birthing, to human groping and rape, to mind control and accidental pron (i.e. trying to help someone push through a trap, handle of hammer goes in butt, they orgasm from aphrodisiacs). This means there's not a lot of any one thing but there is a lot of variety, tho 90% are with Mary, the MC (girl on cover) and she herself wears a shapeshifting tentacle suit that gets a lot of time too.
Gameplay wise, it's actually kinda cool. There is one massive mostly interconnected world, but the game lets you instantly travel to hotspots via world map and is generous with locations to spawn (start of map, start of cave, start of resource hut, etc) and you can go back to the world map whenever.
Despite being an RPG maker game (and ultimately being unable to escape that fact...) the devs tried to spice up the combat with some complexity. Every hero is unique in interesting ways, some are specialized frontline tanks, some get targeted less in the back, some can't wear panty equipment, etc, and they all have EX forms which shift how they play. I.e. a phalanx girl pulls her greatshield out in EX mode, allowing her to use defensive buffs and attack skills that scale off defense. The ice spirit melts into a water one her EX form, using ice/water magic depending on form, but then the soak status effect from water magic makes inflicting the freeze status more likely, so there is internal synergy for some characters too. EX form abilities and perks typically use TP instead of MP, so you have a cool ying/yang kind of system there.
Lots of accessory items also give you good abilities, letting you give heals to someone without them, or attacks to someone with only buffs.
There is also a base-building portion which while not extensive is still something you will likely spend time on, and the currently recruited cast is scattered throughout the base (and many non-dungeon areas like towns, actually) with bits of things to say, which is impressive for an indie ero game.
Overall, I quite enjoyed it, and frankly it might be their best work yet. It's definitely not for everyone, but if you liked their previous work chances are you will love this one provided you make it past that terrible opening wheel of side stories or skip them (don't feel bad about skipping them).