If "the Chinese" wish to convince the world that they are only capable of nursing centuries-long grudges, then that would be the way to do it.

Is there latent resentment of Japan amongst ordinary people? Yes, but how much of that is the product of the Party's deliberate narrative making?

My own take on this is that the anti-Japanese sentiment in China is as much a manufactured artifact of the Communist Party as it is the result of community and family lore.

Most of us understand that the Party depends on narratives that shift public attention away from their various pathologies (most notably their willingness to suppress all opposition to the Party and its policies). Hatred for Japanese imperialists, real (in the past) or imagined (in the present) fits the bill nicely.