Kimura seized the opportunity to step up to a higher category, which was the primary reward for the top ranker among HFDP drivers, albeit the 3rd place in the F4 series; and thus, he was invited by B-Max Racing Team to run in the SFL series from this season.

Kimura started pre-season practice with much expectation to himself, however, he immediately bumped into a trouble that was unforeseen to almost anybody. The G-force generated by SFL car was way too high for his neck to bear, and he had to stop the session soon after it started.

“I was told beforehand that Suzuka would be (physically) tough for me. So, I tried my best to prepare for the test, but the intensive training as hard as I could ever imagine was just good-for-nothing.”

The performance of SFL cars is much higher than that of FIA-F4 cars in all areas such as engine power, downforce, tire grip and so on, which significantly increases the physical burden to the driver. Kimura was overwhelmed by the load and injured his neck muscles.

“All I could do was just to watch from the pit drooling over everyone else running razzle-dazzle. I was so frustrated and felt miserable to myself. I realised by the real stint that the physical stress was incredibly higher than the car I drove before. It’s like chalk and cheese to me, really! When you get tired and lactic acid build up in the muscle, it’s quite normal your neck would peter out. As I begun another stint after changing used tires to new ones, the grip level increased all at once, which was far beyond the F4 level, and “ouch!” I felt my neck kinda snapped. That’s how the damage occurred.”

When turning a corner at high speed in a formula car, driver’s head is pushed outside due to the centrifugal force. If the G-force prevailed and tilted your head outside, your visibility is retarded and you won’t carry on racing. In order to prevent this, racing drivers are always training neck muscles to cope with the centrifugal force. Kimura, of course, did the hardest possible workout, however, the performance level of SFL cars plainly surpassed his assumptions.

Some drivers, giving up his muscle fight against the G-force, prop one's head against the protection paddings installed at both side of the cockpit. But Kimura is disinclined to employ such a style.

“It hinders my sight and the feeling of the semicircular canal may also change, which would bring some risks such as the reaction or operational delay. As for particular corners I'd known beforehand that I can go full throttle, it’s OK to hit on the gas casually while pressing the helmet to the padding. But, if you need to maneuver the car on an ad hoc basis, you can’t go quick and smooth in that way. I wonder if it’s possible depending on the amount of the experience, I don’t know. Anyway, I think the reclined helmet looks awkward in the first place, so I’d rather go with my neck trained bullet-proof.”

Regarding this stumbling at the very outset, Kimura thinks now that his determination towards the formula car racing hasn't been strong enough.

“My awareness of the physical condition was not proper enough either. I thought I'd been well trained and physically ready to compete in the race, but reality was the shortfall in every aspect of the formula racing qualifications. In FIA-F4 days, I was often off to the track in the morning straight from the bed, sat in the car and drove, somethin' like that. But now, I do warm-ups, take essential amino-acid drinks, pump up heart rate before the session, and many other preparatory stuff. I’m now becoming more conscious about the aftercare too, such as body massage, cooldown exercise and else. In the past, I didn’t care much about my muscles that’s worn out after the race. If I’d done it properly, the suffering in Suzuka test would never happened, for sure.”

SFL debutant, Kimura has some other shortcomings besides the physical toughness. He simply needs more experience and ability in order to compete in the SFL car that has much higher performance and to make full use of it. One example standing out from others is the tire management.

As for FIA-F4, so-called "control tires" are designed/manufactured to keep the performance as consistent as possible throughout its life, because FIA F4 is the introductory class to the formula racing, and its format is elaborated so as to enable entrants run under stable conditions, accumulate the milage and learn the basic skill of racing. The tires for SFL, on the other hand, are intended to perform best at the specific working range useful in the battle mode, in other words, having very peaky quality that functions extremely well but wears correspondingly quick. Therefore, each driver is being questioned whether one has the skill to exploit the tire with such a “pointy” character.

“I found that the biggest change was tires. FIA-F4 tires neither have the peak nor the life end whereas SFL tires have both. A stark contrast! In qualifying sessions, we need to adjust the peak point and use it as much as possible. In the race, we have to save tires as well as cope with the wear, which means the driving style is totally different between the qualifying run and the race. I think this is the main challenge so far to me. Actually, in this very first race, I didn’t know how to drive with the finishing tires, and I was left behind while looking for my own answer. After I grasped some feelings, I could catch up and marked the fastest time. That’s nice, anyway…”

Kimura, after stepping up to the SFL series, participated in 3 races in the first race weeks, and finished 2nd twice in R-1 and R-3, albeit sank to 6th in R-2.

“It was my first race week and I had no idea what would happen in the imminent races. So, I told myself to carry on all through to the end, just never ever give up!  I’ve got two podium finishes, so far so good. This very weekend taught me there’re so many things that I don’t know yet, and I’ve bumped around all over the place. But, there’s a total of 18 races and just one had finished. It’ll be a long way to go. The fact that I could get a podium finish in my maiden race is a result that some essential factors are coming together, I convince myself.”

The “coming-of-age” story of Kimura who humbly admits “still lot to learn” has just started.