I've been trying to figure out how realistic this "Important Notice" is, and all I can think of is, "Not very."
Important notice for Japan Tourist modelsSo let me get this straight: A foreigner-friendly computer which can be serviced in Japan and, so far as I can tell, can be purchased only in Japan, should not be used in Japan.
Tourist models are neither designed nor manufactured for the use in Japan.
Refrain from using them in Japan.
If these Overseas Models were super-duper, state-of-the-art computers available only in Japan, and if this were a gimmick to increase tourism to Japan ("Visit Japan, get a new computer, and be the envy of other foreigners!"), that might make sense. But they're not, and it isn't.
Edit: I should point out that Sony's own website states that Sony Overseas Models are "products that you can use both in Japan and overseas."