2016–20 At the
2016 Latin American Table Tennis Championships, Ishiy won two gold medals in mixed doubles and team, and two bronzes in singles under-21 and doubles. At the
2017 World Table Tennis Championships, participating in the mixed doubles together with Kumahara, Ishiy won the 1st round, but were eliminated in the 2nd round. At the
2017 Pan American Table Tennis Championships, Ishiy won three gold medals in doubles, mixed doubles and team. At the
2018 South American Games, he won three gold medals in singles, mixed doubles and men's team, and a bronze medal in men's doubles. At the
2018 Pan American Table Tennis Championships, Ishiy won two gold medals in doubles and team. Ishiy's biggest individual title was gold at the
2019 Pan American Table Tennis Championships, held in Asunción, Paraguay. At 23 years old, and being 121st in the world rankings, he was not among the big favorites and overcame several traditional opponents from South America. Ishiy beat home player Marcelo Aguirre (54th in the world) in the round of 16, and Colombian Alberto Mino (75th in the world) in the quarterfinals. In the semi-final, he faced his compatriot
Gustavo Tsuboi, 28th in the world, where Ishiy ended up losing by two sets to zero, tied the match, lost the fifth set and again managed to draw. The decisive set was very disputed and decided in the end, in favor of Ishiy: 4 to 3 on the scoreboard (6/11, 10/12, 11/6, 11/7, 10/12, 11/3 and 11/9). Just over 70 minutes after the end of the semi-final, he faced Argentine
Gastón Alto, another experienced athlete from the World Tour, defeating him by 4 sets to 1, with splits of (9–11, 11–3, 14–12, 11–4 and 11–7) to win the gold medal. At the
2019 World Table Tennis Championships, Ishiy participated in the
singles draw, being eliminated in the 1st round. In the
men's doubles,
Thiago Monteiro and Ishiy won the 1st round and played an even match in the 2nd round, but lost the crucial points and the game to the pair Yun-Ju Lin and Tai-Wei Wang, from China Taipei, by 4 sets to 1 (11/5, 9/11, 9/11, 8/11 and 9/11).
2020 Olympic Games Ishiy was at the
2020 Olympic Games in Tokyo, where he participated in the
Brazilian team made up of himself,
Hugo Calderano and
Gustavo Tsuboi. In the round of 16, they beat Serbia 3–2, but in the quarter-finals they were eliminated by South Korea 3–0. 8th position was the best in the country's history, in this modality.
2021–24 At the
2021 Pan American Table Tennis Championships, Ishiy, 63rd in the world, reached the semifinals where he faced the best table tennis player in the Americas of all time,
Hugo Calderano, number 5 in the world at the moment, and ended up being eliminated by 4 sets to 0, however, ending with the individual bronze medal. In the same competition, he won gold in mixed doubles, on the Brazilian team, and a bronze in doubles. At the
2021 World Table Tennis Championships, Ishiy participated in the
singles draw, being eliminated in the 2nd round by
Quadri Aruna, who reached the quarter-finals of the competition. He also participated in the men's doubles and mixed doubles, being eliminated in the 1st round of both. At the
2022 Pan American Table Tennis Championships, Ishiy won two gold medals in mixed doubles and team, and a bronze in doubles. At the
2023 World Table Tennis Championships, Ishiy and Takahashi participated as No.11 seeds in the
mixed doubles competition, where they were eliminated in the 2nd round by the Singaporean pair. Ishiy also participated in the
men's doubles together with Eric Jouti, also being eliminated in the 2nd round. At the
2023 Pan American Table Tennis Championships in Havana, the Brazilian team made up of Ishiy, Hugo Calderano, Eric Jouti and Guilherme Teodoro won gold. With this, Ishiy, Hugo Calderano and Eric Jouti won the place to defend the Brazilian team at the Paris 2024 Olympic Games. In this competition, Ishiy also obtained a silver in the mixed doubles together with Bruna Takahashi. In singles, Ishiy beat Puerto Rican Oscar Birriel 4 sets to 3 in the first round, but later lost to Chilean Nicolas Burgos, 4 sets to 2. At the
2023 Pan American Games in Santiago, Ishiy won gold for the
Brazilian team, and silver in
mixed doubles. With this, he obtained a place for the
2024 Summer Olympics in table tennis mixed doubles. Ishiy and Takahashi were ranked 11th in the mixed doubles world rankings at this time. He also won silver in
doubles. In
singles, Ishiy reached the second round, but was eliminated by Chilean Nicolás Burgos, second-ranked player in the Americas, number 54 in the world at the moment. In 2024, Ishiy formed a permanent duo with Guilherme Teodoro. They reached the round of 16 of the Singapore Smash and the Saudi Smash. At the WTT Contender in Rio de Janeiro, they reached the semifinals together, obtaining the bronze medal. At the WTT Contender in Mendoza, Argentina, they reached the final, obtaining the silver medal, and reaching the position of 16th best pair in the world.
2024 Olympic Games At the
2024 Olympic Games, he and
Bruna Takahashi were eliminated in the mixed doubles opener by 4 sets to 2. In the singles bracket, he won his first match in the Olympics, defeating Australian world number 38 Nicholas Lum by 4 sets to 0. In the second round, he faced
Dimitrij Ovtcharov, two-time Olympic bronze medalist, where he still won a set against the German, but ended up being eliminated by 4 sets to 1. He also participated in the
team competition, where Brazil equaled its best ever placing in the Olympics, reaching the quarterfinals.
2024-2028 At the
2024 Pan American Table Tennis Championships, Ishiy was runner-up, losing only to
Hugo Calderano in the final. After winning silver at this competition, Ishiy reached world number 46 in the ITTF rankings in January 2025, the best ranking he achieved in his career. At the WTT Star Contender in Foz do Iguaçu, in August 2025, he reached the round of 16. ==Best results by type of tournament==