I'm American and this doesn't offend me. It's their naval flag, as it was in the late 19th century up until now. The war is over, Japan and America are close allies, hell other countries like Britain, Australia, and a lot of European countries, ones that are supposedly "closer allies" than Japan have a lot more distain and hate towards the US than Japan does. The average remark left by Euros and Aussies on this very website is proof of that. Besides, flying the rising sun flag isn't like flying the swastika.