Karthikeyan will partner home hero Kobayashi at Team Le Mans in the 2016 season that begins at Suzuka on April 24.
The Toyota-powered Team Le Mans is one of the top outfits in Super Formula, seen as the fastest single seater racing series outside of Formula 1. The Indian was with Honda-powered Team Dandelion Racing last season when he finished 11th in the drivers' standings.
Over the 2015 winter, Karthikeyan was set to continue in Super Formula and grabbed the opportunity to race in his third straight season with Team Le Mans just after the New Year. The difficulties faced during last season's campaign were an obvious factor in the final decision as well. So far, his best result has been a third place finish at the 2015 season opener at Suzuka.
"Le Mans is one of the top Super Formula teams with a rich history and I want to use all their experience and knowhow in Japan to deliver a consistent and winning campaign."
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Being teammates with Kobayashi will be a highlight as well - the former Japanese F1 driver is known for his aggressive style particularly in races and has already impressed the paddock on his Super Formula debut last year.
"Of course we will work together to get the best results for the team, pushing each other throughout."
Courtesy the Karthikeyan-Kobayashi duo, Team Le Mans will be the only team on the grid boasting of Formula 1 drivers on both sides of their garage. However, the competition continues to be fierce with extremely high-quality and credible drivers making up the grid once again.
Other big names include former Force India F1 test driver James Rossiter (UK), reigning champion Hiroaki Ishiura (Japan) and another former series champion Joao Paulo de Oliveira (Brazil).
After being powered by naturally-aspirated V8 engines for well over a decade, Super Formula series switched to two-litre, 550bhp turbocharged engines in 2014 - in line with new turbo Formula 1 regulations which also came in force in the same year. The cutting-edge Dallara SF14 chassis has proved to be excellent as well, producing high levels of downforce while allowing for close racing at the same time given the competitive nature of the series.