Webike Japan (Japan's biggest online Motorcycle accessory retailer) is now selling Japanese market version of SHOEI helmet.
http://japan.webike.net/brd/SHOEI/666/ (http://japan.webike.net/brd/SHOEI/666/)
(All SHOEI helmets for North American Market have internal shape for oval head. (not extreme, but they are definitely NOT for rounder head shape.))
Those "Japanese market models" have much wider room at temples.
Also, there are subtle differences such as GT-Air and Neotech having micro-ratchet chin strap system instead of double D-ring.
Right at this moment, GT-Air with solid color is $400.8, so the pricing is not bad.
I personally want this one : Z-7 (not available in US market)
http://japan.webike.net/products/21434591.html (http://japan.webike.net/products/21434591.html)
So, as the title says, if you wanted and tried GT-Air , RF, X-12, etc, but gave up because of the head shape, at least there's an option now.
(Disclaimer : If you buy helmet this way, please keep in mind that those helmets don't have DOT stickers. So they are illegal to use on the road ,technically. That said, I've done it many times (privately imported helmet, no DOT sticker), I've seen many people did the same thing here in Bay area. )