Tadasuke Makino remains the only race winner in Japanese F4, having picked up the win in the second race at Okayama.
Fifth on the grid, Makino watched the rivals ahead of him rule themselves out of contention, caught out by the treacherous conditions on a very wet track.
After a safety car start, the standing water on-track claimed its first victim in poleman Tsubasa Mekaru, who spun and tagged second-placed Shintaro Kawabata.
Shinnosuke Yamada then took the lead, only to spin out in the hairpin, handing first place to Makino.
The race for the win was basically over at that point as the championship leader began to storm away from the rest, finishing ten seconds in the clear.
Shou Tsuboi picked up a second consecutive runner-up finish, with Honda Dream Project’s Hiroki Ohtsu claiming third.
Having started in 14th, James Munro made it up to sixth and was moved up to fourth when Yuichi Mikasa and a recovering Mekaru collided ahead of him.
Yuta Kamimura took fifth, while Nicolas Costa and Mizuki Ishizaka took the flag behind him, only to be penalized for overtaking under yellows.
As such, Yuki Shiraishi and Yuya Hiraki were promoted to sixth and seventh, while Noa Satomi, Katsuhide Kaneishi and Yuki Nemoto rounded out the top ten.
|1||Tadasuke Makino||RN-S||15 laps in 30:27.088|
|2||Shou Tsuboi||TOM’S Spirit||+10.200|
|3||Hiroki Ohtsu||Honda FDP||+14.150|
|5||Yuta Kamimura||Honda FDP||+23.374|
|6||Yuki Shiraishi||Team A-One||+45.296|
|7||Yuya Hiraki||RS Fine||+54.336|
|8||Noa Satomi||Le Beausset Motorsports||+58.438|
|9||Katsuhide Kaneishi||Honda FDP||+1:01.581|
|11||Takahiro Ban||Sutekina Racing Team||+1:15.963|
|12||Ryo Yamada||Garage Chabatake||+1:17.793|
|13||Yoshiaki Katayama||ma with SARD||+1:18.958|
|14||Yuya Tezuka||Field Motorsport||+1:23.588|
|15||Nicolas Costa||VSR Lamborghini||+1’23.592|
|16||Mizuki Ishizaka||Honda FDP||+1:24.975|
|17||Riku Hashimoto||Skill Speed||+1:26.740|
|18||Takuro Shinohara||VSR Lamborghini||+1:31.166|
|19||Junpei Kato||ma with SARD||+1:34.865|
|20||Shunsuke Kouno||RS Fine||+1:37.849|
|21||Takashi Hata||Field Motorsport||+1 lap|
|22||Katsuaki Kubota||Hanashima Racing||+1 lap|
|23||Masanori Yonekura||Yonekura||+2 laps|
|24||Yugo Tabe||N Speed / S2R||+2 laps|
|Yuichi Mikasa||B-MAX Racing||+5 laps|
|Tsubasa Mekaru||Media Do Kageyama||+5 laps|
|Shintaro Kawabata||Succeed Sports||+13 laps|
|Shinnosuke Yamada||B-MAX Racing||+13 laps|