Mugen driver Sasahara was the prime beneficiary of the second of two safety car periods in an eventful 40-lap race, triggered by the Impul machine of Sekiguchi stopping after losing its left-rear wheel.
Sekiguchi had just exited the pits well clear of early-stopping rival Tomoki Nojiri at the end of lap 25, thanks to a lightning quick mandatory pitstop, having led the entire race up to that point from pole.
But the stop proved to be too hasty as Sekiguchi spun exiting the Turn 10-11-12 complex on his out-lap, his left-rear having parted company with the rest of his Impul car.
His stoppage played right into the hands of those drivers that had still yet to make their stops at that point, with Sasahara taking the lead after pitting on lap 27 and front-row starter Sho Tsuboi - who came in on the previous lap - moving up to second, barely nosing ahead of Nojiri at the pit exit.
At the restart on lap 31, Sasahara streaked away from Inging driver Tsuboi, reeling off the remaining laps without drama to claim a first Super Formula win by a margin of just over two seconds.
Points leader Nojiri attacked Tsuboi for second on the restart, but couldn't get the move done and had to turn his attentions to defending third from TOM'S driver Ritomo Miyata, another driver to benefit hugely from the second safety car period having started from last on the grid.
Nojiri nevertheless came away with an enhanced championship advantage of 29 points as both of his main title rivals, Ryo Hirakawa and Sacha Fenestraz, were eliminated in separate on-track incidents.
Hirakawa, who qualified 11th in the second Impul car, was taken out exiting Turn 1 as he was tapped from behind by the Nakajima Racing car of Toshiki Oyu, with Team Goh's Atsushi Miyake also caught up in the ensuing melee.
Kondo Racing man Fenestraz only made it as far as the start of lap three before crashing heavily into the barriers on the exit of Turn 2, an incident that caused the first safety car period.
Fenestraz had been defending seventh from a fast-starting Naoki Yamamoto in the other Nakajima car, who had made up an enormous amount of ground from 17th on the grid, but exiting Turn 1 the Franco-Argentine driver moved left to defend from Yamamoto, who moved slightly right to trigger the contact.
The stewards blamed the Nakajima drivers in both incidents, with Oyu and Yamamoto both serving drivethrough penalties.
After serving his penalty, Yamamoto resumed right in front of Nojiri - who was first to pit when the window opened on lap 10 - and appeared to be holding up his Honda colleague, allowing Sekiguchi crucial breathing room at the head of the field.
Another of the early stoppers, Tadasuke Makino (Dandelion Racing), came home fifth ahead of Red Bull junior Ren Sato (Goh), another driver to be able to serve his mandatory stop under the safety car.
The surviving Kondo machine of Kenta Yamashita was seventh after being passed late on by Sato, while Yuji Kunimoto (KCMG) and the recovering Nakajima cars of Yamamoto and Oyu completed the top 10.
Giuliano Alesi (TOM'S) was a non-finisher after experiencing car trouble during his pitstop, while Nobuharu Matsushita (B-Max Racing) spun exiting the last corner on the formation lap, triggering another green-flag tour.
Result - 40 laps
| Cla | Driver | Team | Gap |
|---|---|---|---|
| 1 |
 Ukyo Sasahara | Team Mugen | |
| 2 |
Sho Tsuboi | P.MU/CERUMO･INGING | 2.098 |
| 3 |
Tomoki Nojiri | Team Mugen | 7.549 |
| 4 |
Ritomo Miyata | Kuo VANTELIN TEAM TOM’S | 8.854 |
| 5 |
Tadasuke Makino | Dandelion Racing | 13.454 |
| 6 |
Ren Sato | Team Goh | 14.116 |
| 7 |
Kenta Yamashita | Kondo Racing | 15.660 |
| 8 |
Yuji Kunimoto | KCMG | 18.438 |
| 9 |
Naoki Yamamoto | TCS Nakajima Racing | 19.258 |
| 10 |
Toshiki Oyu | TCS Nakajima Racing | 21.269 |
| 11 |
Nirei Fukuzumi | ThreeBond Drago CORSE | 22.350 |
| 12 |
Sena Sakaguchi | P.MU/CERUMO･INGING | 27.097 |
| 13 |
Kazuya Oshima | docomo business ROOKIE | 28.396 |
| 14 |
Kamui Kobayashi | KCMG | 30.040 |
| 15 |
Hiroki Otsu | Dandelion Racing | 30.696 |
|
Yuhi Sekiguchi | Team Impul | 15 Laps | |
 Giuliano Alesi | Kuo VANTELIN TEAM TOM’S | 20 Laps | |
|
Sacha Fenestraz | Kondo Racing | 38 Laps | |
|
Nobuharu Matsushita | B-Max Racing Team | 38 Laps | |
|
Atsushi Miyake | Team Goh | 39 Laps | |
|
Ryo Hirakawa | Team Impul | ||
| View full results | |||
