Having scored three bonus points for pole position in qualifying earlier on Saturday, Nojiri only needed a top-three result to become Super Formula's first back-to-back champion since Tsugio Matsuda in 2008.
But the 33-year-old wrapped up the championship in style with a strong run to second, as his chief championship rivals Sacha Fenestraz and Ryo Hirakawa could manage no better than 16th and ninth respectively.
