Shioda started Race 1 from pole alongside Shirasaki, but a damp track and mixed tyre choices quickly reshaped the order. While Shioda and Shirasaki led early, Masaki Hamabe’s struggles on slicks opened the door for the chasing pack. Sakai moved forward as drivers ahead made mistakes, passing Haruto Nakai and Shirasaki before overtaking Ryutaro Sakai for the lead through Turns 6 and 7.
The closing stages brought another shift. Leon Ochiai charged from 21st to second by Lap 11, while Kenta Kumagai climbed from 12th to third before a late Safety Car froze the order. Ryo Sakai took his first Japanese F4 win ahead of Ochiai and Kumagai. Shioda slipped to ninth as the track dried, while Shirasaki finished 12th, ending his six-race winning streak.
Sunday's Race 2 was run in heavier rain, with Shioda and Shirasaki starting from the front row. The race began behind the Safety Car before going green on Lap 3, and Shioda immediately established control. He built a lead of more than seven seconds over Shirasaki before another late Safety Car, triggered by Buntaro Igarashi spinning, brought the field together for the finish.
Shioda held on for his first Japanese F4 victory, with Shirasaki recovering to second and Haruto Nakai taking third.
Despite losing his winning streak on Saturday, Shirasaki leaves Sugo with his championship lead extended to 60 points over Sakai. The Japanese F4 season now heads to its final round at Autopolis in October.
