Japan’s Record Holder Mitsunaga Tests Positive, Will Still Compete This Summer

102nd JAPAN SWIMMING CHAMPIONSHIPS

• Thursday, June 4th – Sunday, June 7th
• Tokyo Aquatics Centre
• LCM (50m)
• Meet Central
• Livestream

With the 102nd Japan Swimming Championships nearly upon us, as action is set to kick off on Thursday, June 4th, the nation’s swimming federation (JASF) has revealed a recent doping violation on the men’s side of the elite swimming squad.

Today, Tuesday, June 2nd, the Japan Anti-Doping Agency (JADA) revealed that national record holder Shoon Mitsunaga was suspended for four months, beginning on November 5th, 2025, for a doping violation.

According to Asian media, Mitsunaga tested positive for the banned substance tulobetrol, a chemical which reportedly opens the bronchi. The banned substance was reportedly detected in a doping test at the Japan Intercollegiate Championships in September of 2025.

The four-month ban reportedly began on November 5th, 2025, and ended on March 5, 2026, meaning his 50m butterfly Japanese national record of 23.06, set in March of this year, still stands.

As a result of that performance, in addition to his gold medal-earning swim of 51.32 in the 100m fly, Mitsunaga remains on the Japanese roster for this year’s Pan Pacific Championships and Asian Games.

The Japan Swimming Federation has established internal regulations in early March, allowing Mitsunaga to participate in the 102nd Japanese Swimming Championships if his suspension was lifted by the day before the race. The internal regulations have not been made public, raising questions about their fairness, and the Japan Federation has stated that it “plans to make them public in the future.” per Sankei.com.