Ex-Formula 1 driver Narain Karthikeyan will step down from his Honda Super GT seat in 2020 to "continue his racing pursuits in other series".
Karthikeyan joined the Japanese series at the start of the 2019 season with Nakajima Racing, marking a major shift to sportscars after a career largely based in single-seaters.
He and Nakajima Racing team-mate Tadasuke Makino initially struggled for results in the opening half of the season, before scoring a breakthrough podium in a weather-affected Sugo race in September and went on to finish 12th in the championship.
Karthikeyan then single-handedly won the second leg of the non-championship SUPER GT x DTM Dream Race at Fuji, overcoming three separate safety cars in an attritional race.
However, ahead of Honda's annual motorsport programme announcement on January 10, Karthikeyan has confirmed that he will not continue in SUPER GT for a second season.
The 42-year-old has yet to announce his plans for 2020, but a statement read that he will "focus his attention to developing his other automotive related business ventures" while continuing racing in an as yet unknown series.
"2019 has been an amazing year for me, but also a mega-busy one," Karthikeyan said.
"I've travelled to Japan so many times I've lost count actually.
"My year ended in the most amazing way ever - by winning the DTM x JSGT Dream Race.
"I would like to say thank you to Satoru-san and the entire Nakajima Racing family for making it such a fantastic year.
"I have raced with them for a few years now in Japan, and it really feels like I have a second family in Japan.
"It's been such a privilege to work with all of them, especially Nakajima-san himself, who is a true legend of motorsport.
"The teams of people at Modulo, Honda Racing as well as Dunlop Tyres have also been so amazing to work with, and I am very lucky to have had their complete trust and support."
Karthikeyan graduated to Formula 1 in 2005 for a single season with Jordan, and then competed at the likes of Le Mans and in the NASCAR Truck Series (pictured below) alongside single-seater programmes including A1GP and Superleague Formula.
He secured an F1 return with HRT for 2011, contesting two seasons, and then switched to racing in Japanese Super Formula after a season in AutoGP in 2013.
In 2017-18 he raced for Nakajima Racing in the Super Formula category, but his best year came in 2015 when he finished 11th.
Following Karthikeyan's departure, Nakajima Racing is expected to feature an all-new line-up comprising SUPER GT stalwart Takuya Izawa and GT300 graduate Hiroki Otsu.
Makino could move across from Nakajima to Kunimitsu, replacing Jenson Button alongside Naoki Yamamoto.