Simon Cox was the assistant chief designer, but focused primarily on the interior styling (the VX prototype has a billet style center pillar with guages attached to each side, motorcycle style - it also had a pop-up TFT for the nav - Cox is most famous for the Lotus Elan interior).

My understanding was that the principal design lead for the VX project was Satomi Murayama, chief designer/manager at Isuzu's European office in Brussels. Other designers include Joji Yanaka, Andrew Hill and Nick Robinson.

I'm not sure how Shiro Nakamura fit into the picture, but perhaps he was the design department head of Isuzu EU at the time.

A little more information here:
http://www.wildtoys.com/Vehicross/history.asp

-- John