Do Umineko Project's files use downsized/converted format? Or how do I make Umineko Project's size smaller?

[Tappy-tech]

So, I've heard that Umineko Project's size can be converted from 11 GB to 4,5 GB, according to a Reddit post. I assume it's by using ONScripter's NSAConverter script (or whatever is used to convert/downsize ONScripter's files).
I want to know in advance whether it's ACTUALLY possible to do so (or downsize it by other means), since I don't have enough space on my device to play it.

[Tappy-tech]

Anyways, just downloaded UmiProj in its entirety. Here's what I discovered for my questions:
• The files don't use converted/downsized format
• The game takes 11,78 GB
Now to try downsizing it...

[Tappy-tech]

Uh, what would be the ONScripter executable in Umineko Project?