> I get the impression that on futaba trolling is largely ignored and/or embraced, if that makes any sense.

It does. There's entire boards on 2ch.net devoted to collecting kopipe (like the Yoshinoya rant), trolling material and strategies and so on. You could say that the Japanese are pretty much familiar with their usual forms of online communication (never seen anyone on Futaba ask What's sage? ^^) - somehow the same does not seem to hold true for the west / rest of the internet.