Kengo, an 18-year-old Mongolian sumo wrestler collapsed on Thursday and remains in a coma following brain surgery.
The wrestler, whose real name is Baatarkhuu Turutvshin, complained of neck pain and collapsed at a bath house, according to the Japan Sumo Association.
He was rushed to the hospital and doctors removed a hematoma from the jonidan junior-division wrestler's head, the Tokyo Police say.
Kengo belongs to jonidan, the second-lowest of the six divisions in professional sumo wrestling.
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