Just looked at the Japanese video (sorry for taking a while, lost track.). This is what Sigma said in Japanese:
This was right after Vile (well, technically VAVA, but still...) declared Sigma insane, yet before leaving the cell.
You can find it here:
And it comes with subtitles (I had to add in the periods due to the subtitles not having any punctuation).
This is what Bing Translator claimed was the translation (it might be a bit wonky, though):
"No compulsion is not a thing that anyone can do. Must be able to go mad."
At the very least, the gist of it is pretty much the same as in the English version. Of course, if you know Japanese well enough to spot-translate it, feel free to verify it on your own time.