Having won three of the five races coming into Motegi, Nojiri only needed to finish inside the top four to guarantee himself of the 2021 drivers’ crown, irrespective of how his rivals Yuhi Sekiguchi and Toshiki Oyu fared in the penultimate round of the season.
While the Mugen driver fell short of that target by one position, a fourth place result for Sekiguchi and a non-score for Oyu means he will take an unassailable points lead into the final race at Suzuka later this month.
He becomes the first driver to seal the championship with a round to spare since Loic Duval won what was then known as Formula Nippon in 2009.
On a wet track, polesitter Otsu successfully fended off a fast-charging Naoki Yamamoto to hold the lead into Turn 2, as Nojiri slipped from third to eighth after a horrible opening lap of the race.
While the 32-year-old pulled away cleanly at the start and held his position in the first sequence of corners, he came under pressure from Sena Sakaguchi at Turn 5 and continued to lose positions for the remainder of the lap.
However, Nojiri was handed a lifeline when title rival Oyu ran over the gravel at Turn 2 – possibly after a collision – suffering a flat tyre in the process.
Back in front, reigning champion Yamamoto started reeling in Otsu as the track began to dry, closing within a second of the Mugen driver by lap 8.
Just when it looked like Yamamoto may be able to take the lead and turn around his season, Super Formula returnee Sacha Fenestraz lost control of his Kondo machine at Turn 5, having been one of the first drivers to switch to slick tyres, bringing out the first safety car of the race.
Otsu immediately dived into the pits at the end of lap 11 and was followed by nearly the entire field, with Yamamoto, Ryo Hirakawa and Nirei Fukuzumi the only drivers to stay out.
As it turned out, the track dried further by the time safety car period ended on lap 13, dropping Yamamoto down the order when he finally made his pitstop three laps later.
This put Otsu well clear in the lead ahead of Sakaguchi and Tadasuke Makino, who had charged his way through the field after qualifying seventh.
Two more safety car appearances had the potential to wreck Otsu’s chances of a maiden victory in Super Formula, but the rookie was able to fend off Sakaguchi on both occasions.
First, Tatiana Calderon spun out of the race on lap 18, suffering severe damage to her Drago Corse car in the process. Then on the restart, a lapped Oyu suddenly slowed exiting Turn 2 – ostensibly to allow the rest of the field to pass him – triggering a major crash going into the next left-hander.
Oyu’s Nakajima Racing teammate Yamamoto suffered the biggest damage when he hit the wall on the inside of Turn 3, while both Inging’s Sho Tsuboi and Impul’s Hirakawa also ended up in the gravel at the same corner.
When the race restarted for a third time, Otsu pulled away cleanly from the rest of the field, with Sakaguchi chasing him in second position.
At one point Sakaguchi closed right in on Otsu, but the Mugen driver shut the door on him and went on to win the race by just under two seconds.
Makino bagged the final podium position in third for Dandelion Racing after repassing the Impul machine of Sekiguchi into Turn 3 on the penultimate lap of the race, with Nojiri finishing not far behind in fifth to seal the drivers’ crown with a round to spare.
Sixth place went to Nobuharu Matsushita in the sole B-Max Racing car, the ex-Formula 2 driver dropping positions after running as high as fourth in the first stint of the race.
TOM’S Kazuki Nakajima was seventh in only his second Super Formula appearance of the season, while Kenta Yamashita finished a disappointing eighth after starting on the second row of the grid, albeit scoring his and his Kondo team’s first points of the year.
The top 10 was completed by Ritomo Miyata in the second of the two TOM’S cars and the KCMG entry of Kamui Kobayashi.
The latter jumped from 18th on the grid to ninth with a charging opening lap, before slipping back down the order and losing further ground with an early call to switch to slick tyres. However, the drama that ensued ahead of him allowed him to grab the final points-paying position.