The Rising Sun is still used by the Japan Self-Defense Forces with only the Japan Air Self-Defense Force having a different flag (same Roundel however), South Korea didnt object back in '52 when it was adopted and only started making a fuss recently (as in 2012 recently).
China apparently doesnt make a fuss because ... they use it or rather they use asahi pattern since Mao was apparently fond of the design and was used in propaganda posters and apparently still in use so complaining about it would be ... counter-revolutionary and you dont want to be against the people revolution now do you Tongzhi?
In short, only Korea complains about it and lets not look too deep over exactly who is complaining ...