The 20-year-old had said previously she was aiming to return to competition in October so her reported comeback will come earlier than expected.
Both public broadcaster NHK and Kyodo News Agency reported on Tuesday that Ikee would be competing at a Tokyo Swimming Association sanctioned meet on Aug. 29, according to sources.
The event takes place at Tatsumi Swimming Centre, which was due to host water polo at the Tokyo Olympics but the Games was postponed until 2021 because of the coronavirus pandemic.
Ikee, who won six titles at the 2018 Asian Games and was considered a strong medal contender for the Olympics before her illness, took part in an event marking the start of the one-year countdown to the rearranged Tokyo Olympics on July 23.
Ikee spent 10 months in hospital battling the disease and hasn't swam competitively since January 2019. (Reporting by Jack Tarrant; Editing by Simon Cameron-Moore)