Aye, I don't immediately either, but the undertone was there most certainly. After all, sex was pretty much everything the gto mainly kept thinking (or his lack of sex). So in that sense TOKKO just allowed the author to take it one step further and actually show some nudity. Whilst GTO probably isn't meant for the youngest of audience, TOKKO might be targeted for even more mature folk (even if the plot isn't quite equal in quality to many actual seinen series).