On 14 December 2018, FINA conducted an in-competition doping control test on the swimmer Hiromasa Fujimori (JPN) on the occasion of the FINA World Swimming Championships held in Hangzhou, China. The athlete was tested positive to the substance Methylephedrine (Class S.6 Stimulants). 

According to the decision of the FINA Doping Panel, Mr. Hiromasa Fujimori has been found to have committed an anti-doping rule violation under FINA DC Rule 2.1 and he has been sanctioned with a two year (i.e., 24 month) period of ineligibility commencing on 1 January 2019, a date fixed by the Panel pursuant to FINA DC 10.11.1, and ending at the conclusion of 31 December 2020, for his first anti-doping rule violation. All results obtained by Mr. Hiromasa Fujimori on 14 December 2018 were disqualified.

The Athlete appealed the FINA Doping Panel decision to the Court of Arbitration for Sport (CAS) in Lausanne (SUI). The CAS Panel dismissed the appeal of Mr. Fujimori and confirmed the decision of the FINA Doping Panel.