2014–2015 In March 2014, she and
Mima Ito won their first doubles title at the ITTF World Tour German Open. They became the youngest ever winners of the doubles competition on the ITTF World Tour. She was part of the Japanese team at the
2014 Asian Games, but lost to China in the final. In April 2014 she won her second doubles title with
Mima Ito at the ITTF World Tour Spanish Open. In December 2014, she won the doubles title with Mima Ito at the ITTF World Tour Grand Finals in Bangkok. The pair defeated the Singapore pair of
Feng Tianwei and
Yu Mengyu in the semi-finals and Poland pair of
Katarzyna Grzybowska and
Natalia Partyka in the final. On 5 July 2015, Miu Hirano and Mima Ito won the Women's Doubles title at the ITTF World Tour Korean Open. This was their third doubles title since 2014.
2016 In April 2016, she won her first women's singles title at the ITTF World Tour Polish Open by defeating
Yu Mengyu in the final. On 9 October 2016, in the absence of Chinese players, she seized the opportunity to win the Women's World Cup in Philadelphia. She defeated
Mima Ito in the quarterfinals,
Feng Tianwei in the semi-finals, and
Cheng I-ching in the final. This marked her the youngest Women's World Cup champion and the first non-Chinese player to win the title.
2017 On 22 January 2017, she won the All Japan Championships by defeating
Kasumi Ishikawa 4–2 in the final at the Tokyo Metropolitan Gymnasium. On 14 April 2017, she defeated the world No. 1 player,
Ding Ning, at the
2017 Asian Table Tennis Championships. The following day, she defeated the world No. 2
Zhu Yuling in the semi-finals and world No. 5
Chen Meng in the final, setting a new record as the youngest-ever winner of the Asian Championships singles event. She became the third non-Chinese player—and the first since
Chire Koyama in 1996—to win the title. At the
2017 World Table Tennis Championships in Düsseldorf, Hirano progressed to the singles semi-finals before losing to
Ding Ning. By reaching the final four, she secured a bronze medal, ending a 48-year medal drought for Japan in women's singles since
Toshiko Kowada won gold at the
1969 World Championships.
2018–2021 Hirano represented Japan at the
2020 Summer Olympics in the team event, though she did not compete in the singles event. In March, Hirano played in the WTT Doha, but suffered disappointing upsets in both the WTT Contender and WTT Star Contender events, including a loss to
Shin Yu-bin in a potential Olympic team preview. Hirano won silver in the team event at the Tokyo Olympics.
2022–2024 Hirano saw a significant resurgence in the cycle leading to the 2024 Summer Olympics. In July 2023, she won the WTT Contender Zagreb, notably defeating world No. 1
Sun Yingsha in the final. This victory reaffirmed her status as a top-tier threat to the Chinese national team. At the
2024 Summer Olympics, Hirano competed in both singles and the team event. In the
singles competition, she reached the quarterfinals, where she lost a close seven-game match to South Korea's
Shin Yu-bin after nearly overcoming a 3–0 deficit. In the
women's team event, Hirano,
Hina Hayata, and
Miwa Harimoto led Japan to its second consecutive Olympic silver medal. Later in 2024, she contributed to Japan's historic gold medal victory in the women's team event at the
Asian Championships. ==Teams==