I'm going to be crass, but nonetheless here I go.
As Shashi Tharoor would say, history is its own revenge. The past 100 years where Japan first put China to shame by industrializing before it, then became an imperialist beast massacring its people, and then stood tall as the sole East Asian model of modernity are now becoming a blip in the almost 1500 of mutual interaction between the two nations.
The natural order of things is returning and when you think about it, despite what's come to pass Japan's entire culture and social norms are still heavily based on Chinese philosophy, and unlike Korea and Vietnam their language is still tethered to Chinese script. What lasting impact will modern Japan leave on China? China is rapidly catching up in terms of modernization and standard of living. Technologically, Japan is a dinosaur, nothing more needs to be said. The millions massacred in wars have already been replaced by new generations, those who grew up idolizing their media are gradually moving on to other forms of entertainment and subsequent generations will wonder what their parents even found so appealing about those Japanese cartoons.
Today's Japan is a glorified theme park for Westerners enamored with the recent wave of Western produced Samurai content to treat as their plaything, a fitting fate for a country known amongst many things for toys and merchandise. Nowadays, Chinese visiting Japan find their fancy's tickled by playthings of a different sort. Hey, as you say, unlike what the Japanese did in the past, at least the Chinese are actually paying for it and mutually consenting. Best part is that it still doesn't take away from the humiliation, although the not so great part perhaps is knowing amidst all this they deserve far worse.