I was aware that one of China's purpose in campaigning against Japan was to put an wedge between Japan - U.S. Alliance. China does not pick up Britain for the target regardless of its humiliating relation in history with China, because geopolitically Britain has little effects now on China, but the US -Japan alliance is a vital obstruct for the rise of China.
Note that one of the biggest organization that donates representative Honda is anti-Japan Chinese organization. See Sankei(Japanese)
Abiru, a Sankei journalist, points out in his personal blog the possibility of North Korea acting behind the scene in South Korean anti-Japan campaign, based on the new book by Nishioka on the comfort women.
In the book Nishioka points out the fact that some family and relatives of members of Korean Council for Women Drafted for Military Sexual Slavery by Japan, who keep accusing Japan for the issue despite several apologies, were arrested as the spies for North Korea. Abiru says you can not account for all the anti-Japan-ism in South Korea by that, but the possibility of North Korea's involvement behind the scene should be kept in mind/it is vital for North Korea to give a crack on Japan-South Korea alliance. I think the possibility can not be denied just as a conspiracy theory.