Team Tahara Aprilia rider Tanimoto was involved in a serious incident at Turn 1 on the third lap of the fifth round of the season on August 20, hitting the back of the BMW of Taro Sekiguchi and being launched into the barriers.
The crash caused the race to be red-flagged as well as a delay to the schedule that also affected the Super Formula race taking place on the same day.
Tanimoto was airlifted to Dokkyo Medical University Hospital in Tochigi Prefecture in critical condition, having been reported to have suffered a fractured neck.
A statement released by the Tatara outfit on Tuesday said that Tanimoto remained unconscious until he was pronounced dead in the early hours of September 5, a little over two weeks after the incident took place.
Tanimoto was in his first season racing in All-Japan Superbike’s top JSB1000 class, having made the step up from the Stock 1000 category. His best result was 13th.
“I have nothing but words of regret,” said Tahara team manager Tetsugo Inoue. “Otojiro Tanimoto joined our team at the start of the season as a replacement rider.
“After impressing us with his riding and personality, it had just been decided that he would continue with us for the second half of the season when the accident happened.
“I would like to express my gratitude for those who have been supporting Otojiro over the last two weeks, and to those who have been worrying about the team.”
The tragic news of Tanimoto’s passing comes less than a month after another rising Japanese Superbike star, Haruki Noguchi, was killed in a crash during the Mandalika round of the Asia Road Racing Championship.
Autopolis hosted the most recent round of the All-Japan Superbike series last weekend, with two more rounds to follow this season at Okayama and Suzuka.
Yamaha’s Katsuyuki Nakasuga stands on the cusp of his 12th series title having won every race this season so far bar one.