You might want to give the next Japanese arcade machine you play a wipe down first after reading this.
My Tokyo-based friend and fighting game community figure, Scott Popular (he calls me Yankee Blue Jeans for some reason), blogged about a disturbing find at his local arcade in Shibuya. After eating lunch, he stopped by the famed Kaikan arcade to play a round or two when he found a guy...pleasuring himself on/over the King of Fighters XIII Climax machine in the corner. Climax indeed! He says that it took him about five minutes to realize that the guy was "going to town on himself."
Scott bets it was over Mai. I'll back him on that.
Sadly, this isn't the first time he's seen public jacking. Unfortunately, I also witnessed something similar in a horny store in Akihabara a few years back on this strange day.
So yeah. Sanitize. Gloves. Something.