Recalling Honda's small and nimble roadsters from the 1960s, the Honda S660 concept was unveiled this week at the 2013 Tokyo Motor Show. The Japanese automaker describes it as an "an open-top sports-type mini-vehicle," a "kei" car that's set to go into production for the Japanese market in 2015. The concept features a turbocharged three-cylinder engine displacing just 660 cubic centimeters. It's mid-mounted and mated to a CVT gearbox, with power driving the rear wheels only. Peak output is rated at just 64 horsepower, but the performance equation is helped by a total weight of just 2,000 pounds. The production version -- sporting a fully retractable roof -- will be available exclusively in Japan.