There is helmet wearing duty to run on the road in Japan.
Therefore the rider has feelings toward a helmet.
And the owner of many old motorcycles thinks that the latest helmet does not match.
Even if ventilation is comfortable, the owner of many old motorcycles makes much of a style than the comfort.
There is the helmet which is popular among such riders.
It is Arai GP-5X.
This Arai GP-5X does not perform the sale in foreign countries in Japan model.
This model is based on car use, and a shield modified for motorcycles.
Arai Helmet
http://www.arai.co.jp/
http://www.arai.co.jp/jpn/fullface/gp5x_t.html
Of course I own 5X, too.