The number of individuals registering as bone marrow donors reached a monthly record high at 11,662 in February, after teenage swimming star Rikako Ikee announced her leukemia diagnosis the same month, the Japan Marrow Donor Program said Monday.

New registrations exceeded 10,000 for the first time within a month, with the average monthly registration coming to around 2,000 to 4,000.

A total of 503,883 individuals are currently registered with the donor bank, and the majority of registered individuals are in their 40s, with 215,982 people, according to the group.

As the age limit for donors is set at 55, the donor bank will work to increase younger donors at blood donation centers from the next fiscal year starting on April 1.

Treatment for leukemia requires the patient's bone marrow or peripheral blood stem cell to match the donor's. If there is no match within the family, the patient looks to a third party.

"Currently only about 60 percent of patients are matched with someone. We'd like as many people as possible to register as donors, especially those who are younger," a spokesperson for the group said.

The 18-year-old Ikee shot to fame at last summer's Asian Games in Jakarta, where she was named the first female MVP after becoming the first swimmer to win six gold medals, all in games-record times.

She announced her diagnosis last month, sending shock waves and words of support throughout Japan.

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