I think the Jr Idol Club, Gravure Idol Club and JAV Idol Club should have their own busty sub-forum section.
Why?
Are people complaining about big-breasted Jr Idols? If so, I could see the need there: necessary segregation to maintain the peace.
Otherwise, I don't think this is a practical suggestion.
The easy fix,include the cup minimum it in the forum section title for example "Busty Section(D cup US standard or bigger)".Fetish Boundary Disagreement:
Suppose chompy makes a Big Breasts subforum, a Normal Breasts subforum, and a Small Breasts subforum inside of JAV. Suppose somebody then uploads a porn video of a woman with C-cup (Japanese definition) breasts. The flat-chest fan says "THOSE ARE HUGE! GET THOSE OFF OF MY NORMAL BOARD!" The normal fan says, "Those are average. They belong here." And the big breasts fan says, "This is posted in the wrong section. These boobs belong in Small Breasts. Can a mod move this thread, please? Normal is for Japanese D and E only."
You could try to get around this problem by asking a mod to define the limits in a Rules thread, but (a) how many people will read it? and (b) how many uploaders will disagree with the rules and (either because they didn't or because they couldn't read the rules) will go ahead and post their porn where they think it belongs?
Fetish Overlap:
Suppose the JAV Torrents board has subforums for Big Breasts, Swimsuits, and Lotion. Suppose somebody posts a thread for a new porn video where a big-breasted girl wears a swimsuit and smears lotion all over her body? Where is he supposed to post the video? Does it go in all three subforums? If so, where are people supposed to reply if they want to discuss it?