OK! I resolved the "problem":
First of all...the game folder was on a secondary drive that I use for Visual Novels (to not overload the main drive), on a custom folder...and I thought the problem could be that; so I moved the folder to the main drive.
The problem persist
So I deleted the whole folder and extracted the archive directly to the main drive and...IT WORKS! (the same trick works also on the secondary drive)
BUT, there is a but, you must not rename the folder too much; because if you put a numbers in the folder title, then the game no longer works.
For example:
If the folder name is "[LeCode] Wabisabi +18" ; "[LeCode] Wabisabi (+18)" ; "[LeCode] Wabisabi [+18]" or [LeCode] Wabisabi [+18 patch] with also other variations...the game won't work
I simply renamed my folder "[LeCode] Wabisabi (patched)" and it works perfectly.
In the end it was such a stupid problem...it made me feel stupid XD