He is a member of the Honda Formula Dream Project and Red Bull Junior Team and is the 2020 French F4 champion.

Iwasa wrapped up the title with three races still to run by taking a double pole during the final round at the Circuit Paul Ricard.

[6][7] At the start of 2021 Iwasa competed in the F3 Asian Championship, partnering Roy Nissany, Roman Staněk and Reece Ushijima.

[8] He scored his only podium of the campaign in the first race of the fourth round at the Dubai Autodrome and ended up eighth in the championship.

[10] Iwasa's focus for the year would lie in the FIA Formula 3 Championship, where he drove for the same team alongside Staněk and fellow Red Bull Junior Jak Crawford.

[14] At the Red Bull Ring, Iwasa started 19th in Race 1 and finished ninth, but was disqualified due to disobeying the instruction to pit while being shown the black and orange flag.

[19] A difficult round at Spa-Francorchamps, saw Iwasa score no points, but bounced back in Zandvoort with ninth place in qualifying.

He achieved his second podium in Race 1, finishing third behind Arthur Leclerc and Logan Sargeant after reverse polesitter Amaury Cordeel spun.

[23] On 14 January 2022, the French outfit announced that Iwasa would race for the team during the 2022 season, partnering Roy Nissany.

He dropped to third at the start but took advantage of the lap 6 safety car by pitting, which costed the other alternate strategy runners.

[35] In Barcelona, he qualified sixth and started fourth in the sprint race (due to polesitter Calan Williams' stall).

He jumped Théo Pourchaire and Jake Hughes at the start into second, and secure his maiden podium in F2 by remaining in that position.

[40] In the sprint race, he finished 19th albeit last after he forced Clément Novalak into the wall, earning a ten-second time penalty.

[45] In the feature race, a safety car restart on lap 14 when he the back of Jake Hughes causing front wing damage and a trip to the pits, which eventually yielded 14th place.

[47][48] In the feature race, Iwasa had a good getaway at the start, jumping to fourth but a terrible pit stop saw him far from the frontrunners and he finished in 12th.

[67] In the feature race, Iwasa remained fifth at the start, but managed to jump Dennis Hauger in the pit stops.

[68][69] In Monza, Iwasa qualified seventh however, a chance to improve his lap was interrupted by crashing at the final corner in Parabolica.

[70] Starting fourth, Iwasa struggled in the sprint race and slipped back to finish 12th, later being demoted to 16th due to gaining time off-track.

[75][76] After not scoring points in the sprint race, Iwasa duly claimed his second win of the year, despite a late charge from champion Felipe Drugovich.

[81] Iwasa continued with DAMS for the 2023 campaign, alongside Ferrari Driver Academy member Arthur Leclerc.

[90][91] His points streak would come to an end after a broken front wing on the opening lap of the sprint,[92] but in the feature race Iwasa controlled things perfectly for the win and the standings lead.

[93][94] Iwasa struggled in Baku after a poor qualifying left him down in P17 and finished both races outside the points, dropping to third in the standings.

[97][98] He finished tenth in the feature race, after a late red flag saw drivers aheadwho did not pit make up positions.

[100] In the feature race, Iwasa passed Théo Pourchaire following the pit stops, but towards the end was overtaken by a faster Victor Martins, forced to settle with fourth.

[108] Iwasa qualified sixth in Hungary, and a terrific start from fifth moved him to second in the sprint race, where he scored yet another podium.

[109] He opted for the alternate strategy during the feature race which rewarded with a higher finish, ending in fourth place after passing Isack Hadjar late on.

[117] Needing to have take maximum points to even have a chance of winning the title,[118] Qualifying fifth for the Abu Dhabi season finale, he finished eighth in the sprint race.

[128] A disappointing end to the season in the second Suzuka round, owing to poor starts left Iwasa finishing the races ninth and seventh respectively.

[133] Iwasa made his debut in an official Formula One race weekend for the 2024 Japanese Grand Prix, driving for RB in the first practice session in place of Daniel Ricciardo.

[135] Later that year, Iwasa participated in free practice during the 2024 Abu Dhabi Grand Prix, finishing the session in 17th.