Driving the Red Bull-liveried #1 car for Team Mugen, Nojiri was the only driver to break into the 1m35s on Monday, as he posted a 1m35.955s in the closing stages of the two-hour afternoon session.
That was faster than he had managed in qualifying for the final round of the 2022 season at Suzuka in the previous-generation SF19, although it fell short of Sho Tsuboi's best time set in pre-season testing this time last year.
Three-time champion Naoki Yamamoto led a two-three for Nakajima Racing with a 1m36.027s ahead of his new team-mate Ren Sato, continuing the team's encouraging form from last December's post-season test.
Kamui Kobayashi was the best of the Toyota runners for KCMG in fourth place, having sat atop the timesheets before the final flurry of improvements at the end of the session, ahead of Ryo Hirakawa for Team Impul.
Toshiki Oyu enjoyed a strong first day of official testing with the reborn TGM Grand Prix team, ending up eighth-fastest behind Tadasuke Makino (Dandelion) and Tsuboi (Inging).
Red Bull junior driver Liam Lawson was the best of the rookies in ninth place with a best time of 1m36.770s, around eight tenths off the pace of his Mugen team-mate Nojiri.
Completing the top 10 was Ukyo Sasahara, who is standing in for an injured Kenta Yamashita at Kondo Racing for this test.
Sasahara had the only real accident of note of the day during the two-hour morning session when he suffered a crash at Turn 6, bringing out the red flags. His car was repaired in time for him to tackle the final 45 minutes of the afternoon session.
The morning session was led by Yamamoto ahead of TOM'S driver Ritomo Miyata and Dandelion Racing substitute Hiroki Otsu, who were both among a handful of drivers who didn't set better laps in the afternoon.
Otsu is replacing rookie Kakunoshin Ota, who suffered a heavy crash last Friday during SUPER GT testing at Suzuka but like Yamashita was present for the test to observe from the sidelines.
Of the other rookies, TGM's Cem Bolukbasi was 20th-fastest, while B-Max man Raoul Hyman propped up the timesheets in 22nd behind the second TOM'S car of Giuliano Alesi.
Super Formula testing continues on Tuesday with another pair of two-hour sessions planned.
Suzuka testing times:
| Pos. | No. | Driver | Team/Engine | Morning | Afternoon |
|---|---|---|---|---|---|
| 1 | 1 |
 Tomoki Nojiri |
Mugen/Honda | 1'37.424 | 1'35.955 |
| 2 | 64 |
Naoki Yamamoto |
Nakajima/Honda | 1'37.030 | 1'36.027 |
| 3 | 65 |
Ren Sato |
Nakajima/Honda | 1'37.593 | 1'36.083 |
| 4 | 7 |
Kamui Kobayashi |
KCMG/Toyota | 1'37.462 | 1'36.266 |
| 5 | 20 |
Ryo Hirakawa |
Impul/Toyota | 1'37.507 | 1'36.462 |
| 6 | 5 |
Tadasuke Makino |
Dandelion/Honda | 1'37.485 | 1'36.636 |
| 7 | 38 |
Sho Tsuboi |
Inging/Toyota | 1'37.535 | 1'36.640 |
| 8 | 53 |
Toshiki Oyu |
TGM/Honda | 1'37.932 | 1'36.699 |
| 9 | 15 |
 Liam Lawson |
Mugen/Honda | 1'37.923 | 1'36.770 |
| 10 | 3 |
Ukyo Sasahara |
Kondo/Toyota | 1'39.830 | 1'36.789 |
| 11 | 4 |
Kazuto Kotaka |
Kondo/Toyota | 1'38.770 | 1'36.824 |
| 12 | 19 |
Yuhi Sekiguchi |
Impul/Toyota | 1'38.290 | 1'36.974 |
| 13 | 12 |
Nirei Fukuzumi |
ThreeBond/Honda | 1'37.939 | 1'37.092 |
| 14 | 37 |
Ritomo Miyata |
TOM'S/Toyota | 1'37.116 | 1'37.273 |
| 15 | 6 |
Hiroki Otsu |
Dandelion/Honda | 1'37.217 | 1'38.392 |
| 16 | 18 |
Yuji Kunimoto |
KCMG/Toyota | 1'37.576 | 1'37.363 |
| 17 | 50 |
Nobuharu Matsushita |
B-Max/Honda | 1'37.379 | 1'38.653 |
| 18 | 14 |
Kazuya Oshima |
Rookie/Toyota | 1'38.223 | 1'37.555 |
| 19 | 39 |
Sena Sakaguchi |
Inging/Toyota | 1'37.912 | 1'38.743 |
| 20 | 55 |
 Cem Bolukbasi |
TGM/Honda | 1'38.416 | 1'37.972 |
| 21 | 36 |
 Giuliano Alesi |
TOM'S/Toyota | 1'39.504 | 1'38.030 |
| 22 | 51 |
 Raoul Hyman |
B-Max/Honda | 1'39.083 | 1'38.214 |
