Three-time Super Formula champion Naoki Yamamoto has announced his decision to retire from the series following this weekend's season finale at Suzuka.
The Nakajima Racing driver, 36, made the announcement via a post on his Instagram page on Tuesday.
It effectively calls time on a 15-season spell in Japan's top single-seater series for the factory Honda ace which yielded titles in 2013, 2018 and 2020, nine race wins and 13 pole positions.
“It wasn’t an easy decision to make, but I’m extremely grateful for the chance to have competed in Japan’s top category for the last 15 years and all the support I’ve had," Yamamoto wrote.
“I made the announcement at this time so that all the fans watching would know this weekend is the last time you will be able to see me driving a formula car. I believe this is also one of the ways I am able to pay everyone back.
“Whatever the outcome of these final races, I want to step down from Super Formula having shown my real level of performance and having given it my all with this team.”
Yamamoto made his debut in what was then known as Formula Nippon in 2010 with Nakajima before switching to Team Mugen the following season, going on to claim his first two titles with the team.
He elected to switch to Dandelion Racing for 2019 immediately following his second title, which together with his success in Super GT earned him a Formula 1 practice call-up for the Japanese Grand Prix with Toro Rosso.
After winning the 2020 title for Dandelion, Yamamoto returned to Nakajima for the 2021 season, but has struggled to recapture his previous form since then.
His last win came in the wet at Motegi in 2022, although he has enjoyed a slight upturn in form this year, sitting seventh in the standings heading into this weekend's Suzuka double-header.
Yamamoto's decision to step down from Super Formula follows the neck and spinal injuries he suffered in a major crash in last year's SUGO Super GT round, and which required surgery to allow him to prolong his career.
A statement from Honda says that Yamamoto will continue to race in Super GT next season. He currently shares a Team Kunimitsu Honda Civic Type R-GT with Tadasuke Makino, with the pair sitting second in the standings with one race to go this season.