I remember wanting to do the same but never got around to it. The folks over on the Sega Saturn group forums would know for sure if you want to ask directly but I did have this thread bookmarked which might be of interest:
So being impatient like I am I thought I should swap a pal psu into the dead machine. Tested all the pins with a multi meter and it looked sweet, and the Japanese Saturn doesn’t require the 9/12v pin from the pal psu. Plugged it in and its working great. The main reason I’m posting this is that I couldn’t find an example of anyone doing this without some sort of modification. So that if there are others out there wanting to know it can be done assuming you have the right Saturn and the right psu etc. JPN-PAL PSU swap | The Sega Saturn Forum - セガサターン - SegaSaturn.co.uk
No mention of board type though. I’m guessing the 9/12v must be for AV/RGB switching.
Princess Crown was one of my all time favourite Sega Saturn games. I even wrote a review for it a long time ago. Now sadly I only have the PSP version.
I haven’t played it before but heard good things. I’m getting off topic now but I basically have a stack of Japanese games I’ve never tried, so I think it’s a good excuse to start streaming and try some of them out for fun.