You can legally download a boot disk called Utopia, that will legally let you run your legally obtained Japanese game. Just Google it and do a bit of research. If you're running it through SCART then it should be in full colour and speed and whatnot. I've never had any problems booting legally obtained Japanese games with it.
Be aware that some late models manufactured after a certain date will not boot using the MIL CD format that all boot disks exploit. Check the date printed on the underside of your unit. Dec 2000 was I believe when the BIOS was rev'ed