It's also a very sensitive issue in Asia, even in Japan. Many people in Japan tend to associate it with the far right wing, but it is still seen far more often than I'm comfortable with.
That being said, a lot of people here are fundamentally unaware/ignorant of the atrocities that occurred in WWII, ostensibly in their name, because the standardized education system is very whitewashed and textbooks have been chosen for political purposes (many of which paint Japan as the victim - don't get me started on the f*cked up mental gymnastics one would have to do to create books like that.) So they don't see what the fuss is about when people get upset about the Kyokujitsu Ki rising sun flag.
Granted, the current version in use by the JSDF forces is slightly different (the sun is shifted to the left, not dead center like the war flag), so an argument of semantics can occur saying that "it's not the same flag."
On a related note, I've seen people wearing actual nazi insignias/uniforms, and hanging nazi flags in stores being blissfully unaware of how utterly wrong it is. I saw a young woman wearing suspenders (braces for those who speaks the Queen's), with swastika (not the Buddhist kind), and iron cross buttons, 18 hole Docs with red and white laces. I asked her point blank why she was doing it and she said "because it's cute."
Long story short, the rising sun should be retired to the dustbin of history.