Yamamoto has been going through his worst period of form in Super Formula since rejoining Nakajima Racing at the start of the 2021 season, finishing a distant 13th in the championship last year with just 13 points on board.
A second campaign with Satoru Nakajima’s eponymous team also got off to a poor start, with the 33-year-old scoring just two points in the opening four races of the year and struggling to break into Q2 in qualifying.
But last weekend’s Sugo round finally offered a glimmer of hope as Yamamoto set an impressive lap time of 1m05.148s to top the first qualifying group, earning a spot inside the top 12 for only the second time this season.
A mistake on his final flying lap in Q2 meant he ended up slowest, and 11th on the grid after a penalty for Nobuharu Matsushita, but Yamamoto nevertheless took encouragement from his best qualifying performance since Motegi last year, when he bagged a spot on the front row on a wet track.
“We made a lot of progress in getting the top time in Q1 and bringing out the car's condition, and if we can keep driving at this level, I think the results will come,” said Yamamoto.
“It's frustrating that we didn't get a result this time, but I think Q1 was a good qualifying session. I need to get results when I'm in good shape."
Although in-form Mugen Honda man Tomoki Nojiri was in a different league in qualifying as he took his fourth straight pole with a blistering time of 1m04.349s, nearly four tenths up on his nearest rival, there was little to separate drivers from second to 10th on the grid.
Yamamoto felt he could have made a significant improvement over his Q1 effort had he managed to put together a clean lap, explaining that he lost time through Hi-Point corner with dirty tyres after going off-track at the S-curve.
"I should have been able to get into the 1m04s range," he said. "I think I could have got into the 1m04s range. But I didn't actually put the lap together.
“Nojiri was by far the fastest, and at the moment he's not within reach, but I didn't think I'd be able to do 1m05.1s in Q1. I want to keep up this good form and not stray from this good path."
Come the race, Yamamoto was lucky to avoid any damage or penalty for a collision with Kondo Racing's Kenta Yamashita at Turn 1, but his race was effectively ruined when Nakajima Racing accidentally fitted a tyre belonging to teammate Toshiki Oyu’s allocation to his car, forcing him to pit a second time in as many laps.
The extra stop dropped him well down the order and he ultimately finished in 12th place, enduring his fourth non-points finish of the year in five races.
Speaking after the race, Yamamoto admitted that he needs to qualify higher up the grid to improve his prospects for a points finish, having showcased that he is capable of being quick over a single lap in Q1.
“Looking at the results alone, it was a race that didn't go well and I couldn't put it all together, but finally I was able to get to the front in qualifying,” he said.
“It was the first time we had used this set-up, so I was fumbling around a little, but we'll sort things out and move on to the next race.
“As for this race, if you are in that [midfield] group, it's a tough fight even if your pace is good. If I had been able to race a little bit closer to the front, I think the race would have turned out differently.
“This time I made a mistake in qualifying and it cost me, so next time I'll do my best to qualify well."
Oyu bagged Nakajima Racing's first podium finish of the season at Sugo in second place, having qualified fifth.
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