Tsuboi and Miyata carved their way through from 12th on the grid to score their second win of 2023 aboard the #36 Toyota GR Supra and take a seven-point lead in the championship with only the season finale left to run.
In a thrilling and unpredictable 450km race, Miyata caught the long-time leading ARTA Honda of Hiroki Otsu in the closing stint of the race, with the pair engaging in a fierce duel for the top spot.
Otsu had taken over from team-mate Nirei Fukuzumi in the #16 ARTA NSX-GT on lap 59 of 97, while Miyata - who replaced Tsuboi at the wheel of the #36 car at the first round of pitstops - made his final stop on lap 65.
But Miyata fought through from a net fifth place to grab second within a matter of laps, dispatching the points-leading NDDP Racing Nissan of Mitsunori Takaboshi in the process, before closing down Otsu's five-second lead.
By lap 80, Miyata had caught up to the back of Otsu, and after several laps of on-the-limit dicing through the traffic, Miyata made the decisive move up the inside at the Turn 11 hairpin on lap 87.
Miyata went on to take the chequered flag by five seconds, as Otsu held off the NDDP Nissan that Takaboshi took over for the final stint from Katsumasa Chiyo.
The result means that the top three cars in the race are the only cars that can still win the championship in the season finale at Motegi. Fukuzumi and Otsu will head to the finale as rank outsiders in third, 16 points behind Tsuboi and Miyata with 21 on offer.
The Cerumo Toyota of Yuji Tachikawa and Hiroaki Ishiura was fourth after Ishiura made a late pass on the Impul Nissan of Kazuki Hiramine.
The Impul car shared by Hiramine and Bertrand Baguette made up ground from 13th on the grid with an undercut strategy, but fifth place marks the end of their title defence.
Honda squad Real Racing had looked to be in the frame for a podium finish late on, but Koudai Tsukakoshi faded late on to finish sixth in the NSX-GT started by Nobuharu Matsushita.
Next up were two more Toyota squads, the #37 TOM'S car of Ukyo Sasahara and Giuliano Alesi and the Rookie Racing machine of Kazuya Oshima and Kenta Yamashita.
Naoki Yamamoto's stand-in at Team Kunimitsu, Iori Kimura, brought home the NSX-GT he shared with Tadasuke Makino in ninth.
NISMO opted for an unconventional three-stop strategy for the Z shared by Ronnie Quintarelli and Tsugio Matsuda, but it failed to pay dividends and the duo had to be content with 10th.
The #8 ARTA Honda was a non-finisher after Tomoki Nojiri went off into the barriers in his stint, while the SARD Toyota was ruled out by mechanical issues.
Saitama Toyopet closes in on GT300 title
A nailbiting GT300 contest was won by Saitama Toyopet Toyota GR Supra pairing Hiroki Yoshida and Kohta Kawaai, as Yoshida held off the Inging Toyota GR86 GT of Yuui Tsutsumi and Hibiki Taira by just 0.6s.
Tsutsumi appeared to have the edge in the closing stages on fresher tyres, Inging opting for a more conventional strategy of two tyre changes while Saitama Toyopet made it through the distance changing tyres only once.
Yoshida and Kawaai's second straight win puts them on the cusp of the championship, as they lead by 20 points - Tsutsumi and Taira would need to score the maximum 21 points at Motegi and hope their rivals fail to score to overhaul them.
Behind the leading two cars, the new apr Lexus LC500h scored its first podium finish in the hands of Kazuto Kotaka and Yuki Nemoto, who gamely held off the works Subaru BRZ of Takuto Iguchi in the closing stages.
Nemoto ensured a podium lockout for Toyota models and Bridgestone tyres in the process, while the Subaru crew of Iguchi and Hideki Yamauchi made it an-all JAF GT300 top four.
Best of the FIA GT3 finishers was the Kondo Racing Nissan GT-R NISMO GT3 of Teppei Natori and Joao Paulo de Oliveira, who made only one tyre change en route to an impressive recovery from 17th to fifth.
That result wasn't enough however to keep Natori and de Oliveira in title contention, with Team Studie BMW man Seiji Ara likewise dropping out of the running after finishing eighth in the M4 GT3 he shared with Bruno Spengler.
The UpGarage Honda team that was second in the points heading to Autopolis was taken out of the race by the K-tunes Racing Lexus RC F GT3, as Morio Nitta locked up and clouted the rear of Shun Koide's NSX GT3 at Turn 1.
Koide and Takashi Kobayashi were able to continue but finished down in 17th place.
GT500 results:
| Pos. | No. | Car | Drivers | Laps | Gap | Tyre |
|---|---|---|---|---|---|---|
| 1 | 36 | au TOM'S GR Supra TOYOTA GR Supra GT500 |
Sho Tsuboi Ritomo Miyata |
97 | -- | BS |
| 2 | 16 | ARTA MUGEN NSX-GT Honda NSX-GT |
Nirei Fukuzumi Hiroki Otsu |
97 | 5.474 | BS |
| 3 | 3 | Niterra MOTUL Z Nissan Z GT500 |
Katsumasa Chiyo Mitsunori Takaboshi |
97 | 5.854 | MI |
| 4 | 38 | ZENT CERUMO GR Supra TOYOTA GR Supra GT500 |
Yuji Tachikawa Hiroaki Ishiura |
97 | 17.272 | BS |
| 5 | 1 | MARELLI IMPUL Z Nissan Z GT500 |
Kazuki Hiramine Bertrand Baguette |
97 | 18.349 | BS |
| 6 | 17 | Astemo NSX-GT Honda NSX-GT |
Koudai Tsukakoshi Nobuharu Matsushita |
97 | 30.958 | BS |
| 7 | 37 | Deloitte TOM'S GR Supra TOYOTA GR Supra GT500 |
Ukyo Sasahara Giuliano Alesi |
97 | 31.201 | BS |
| 8 | 14 | ENEOS X PRIME GR Supra TOYOTA GR Supra GT500 |
Kazuya Oshima Kenta Yamashita |
97 | 39.206 | BS |
| 9 | 100 | STANLEY NSX-GT Honda NSX-GT |
Tadasuke Makino Iori Kimura |
97 | 1'24.414 | BS |
| 10 | 23 | MOTUL AUTECH Z Nissan Z GT500 |
Tsugio Matsuda Ronnie Quintarelli |
97 | 1'25.131 | MI |
| 11 | 64 | Modulo NSX-GT Honda NSX-GT |
Takuya Izawa Kakunoshin Ohta |
97 | 1'39.210 | DL |
| 12 | 24 | REALIZE CORPORATION ADVAN Z Nissan Z GT500 |
Daiki Sasaki Kohei Hirate |
95 | 2 Laps | YH |
| 13 | 19 | WedsSport ADVAN GR Supra TOYOTA GR Supra GT500 |
Yuji Kunimoto Sena Sakaguchi |
95 | 2 Laps | YH |
| Ret | 39 | DENSO KOBELCO SARD GR Supra TOYOTA GR Supra GT500 |
Yuhi Sekiguchi Yuichi Nakayama |
68 | 29 Laps | BS |
| Ret | 8 | ARTA MUGEN NSX-GT Honda NSX-GT |
Tomoki Nojiri Toshiki Oyu |
41 | 56 Laps | BS |
GT300 results:
| Pos. | No. | Car | Drivers | Laps | Gap | Tyre |
|---|---|---|---|---|---|---|
| 1 | 52 | SAITAMATOYOPET GB GR Supra GT TOYOTA GR Supra |
Hiroki Yoshida Kohta Kawaai |
91 | BS | |
| 2 | 2 | muta Racing GR86 GT TOYOTA GR86 |
Yuui Tsutsumi Hibiki Taira |
91 | 0.612 | BS |
| 3 | 31 | apr LC500h GT LEXUS LC500h |
Kazuto Kotaka Yuki Nemoto |
90 | 1 Lap | BS |
| 4 | 61 | SUBARU BRZ R&D SPORT SUBARU BRZ GT300 |
Takuto Iguchi Hideki Yamauchi |
90 | 1 Lap | DL |
| 5 | 56 | REALIZE NISSAN MECHANIC CHALLENGE GT-R NISSAN GT-R NISMO GT3 |
Joao Paulo de Oliveira Teppei Natori |
90 | 1 Lap | YH |
| 6 | 4 | GOODSMILE HATSUNE MIKU AMG Mercedes AMG GT3 |
Nobuteru Taniguchi Tatsuya Kataoka |
90 | 1 Lap | YH |
| 7 | 88 | JLOC Lamborghini GT3 LAMBORGHINI HURACAN GT3 |
Takashi Kogure Yuya Motojima |
90 | 1 Lap | YH |
| 8 | 7 | Studie BMW M4 BMW M4 GT3 |
Seiji Ara Bruno Spengler |
89 | 2 Laps | MI |
| 9 | 11 | GAINER TANAX GT-R NISSAN GT-R NISMO GT3 |
Ryuichiro Tomita Keishi Ishikawa |
89 | 2 Laps | DL |
| 10 | 10 | PONOS GAINER GT-R NISSAN GT-R NISMO GT3 |
Hironobu Yasuda Riki Okusa |
89 | 2 Laps | DL |
| 11 | 50 | ANEST IWATA Racing RC F GT3 LEXUS RC F GT3 |
Igor Fraga Yuga Furutani |
89 | 2 Laps | YH |
| 12 | 65 | LEON PYRAMID AMG Mercedes AMG GT3 |
Naoya Gamou Takuro Shinohara |
89 | 2 Laps | BS |
| 13 | 20 | SHADE RACING GR86 GT TOYOTA GR86 |
Katsuyuki Hiranaka Eijiro Shimizu |
89 | 2 Laps | DL |
| 14 | 360 | RUNUP RIVAUX GT-R NISSAN GT-R NISMO GT3 |
Takayuki Aoki Takuya Otaki |
89 | 2 Laps | YH |
| 15 | 6 | DOBOT Audi R8 LMS Audi R8 LMS |
Yoshiaki Katayama Roberto Merhi |
89 | 2 Laps | YH |
| 16 | 30 | apr GR86 GT TOYOTA GR86 |
Hiroaki Nagai Manabu Orido Yuta Kamimura |
89 | 2 Laps | YH |
| 17 | 18 | UPGARAGE NSX GT3 Honda NSX GT3 |
Takashi Kobayashi Syun Koide |
88 | 3 Laps | YH |
| 18 | 5 | MACHSYAKEN AIR BUSTER MC86 MACH GO TOYOTA 86 MC |
Yusuke Tomibayashi Takamitsu Matsui |
88 | 3 Laps | YH |
| 19 | 87 | Bamboo Airways Lamborghini GT3 LAMBORGHINI HURACAN GT3 |
Kosuke Matsuura Natsu Sakaguchi |
88 | 3 Laps | YH |
| 20 | 60 | Syntium LMcorsa GR Supra GT TOYOTA GR Supra |
Hiroki Yoshimoto Shunsuke Kohno |
88 | 3 Laps | DL |
| 21 | 22 | R'Qs AMG GT3 Mercedes AMG GT3 |
Hisashi Wada Masaki Jyonai Masaki Kano |
87 | 4 Laps | YH |
| 22 | 48 | Shokumou K's Frontier GT-R NISSAN GT-R NISMO GT3 |
Taiyo Ida Yuki Tanaka Takumi Sanada |
87 | 4 Laps | YH |
| 23 | 9 | PACIFIC VSPO NAC AMG Mercedes AMG GT3 |
Ryohei Sakaguchi Jiatong Liang Shintaro Kawabata |
85 | 6 Laps | YH |
| Ret | 27 | Yogibo NSX GT3 Honda NSX GT3 |
Yugo Iwasawa Reimei Ito |
24 | 67 Laps | YH |
| Ret | 96 | K-tunes RC F GT3 LEXUS RC F GT3 |
Morio Nitta Shinichi Takagi |
21 | 70 Laps | DL |
