Sumo - Japan's national sport wrestles with latest act of violence

FILE PHOTO : Mongolian-born grand sumo champion Yokozuna Harumafuji performs the New Year's ring-entering rite at the annual celebration for the New Year at Meiji Shrine in Tokyo, Japan January 6, 2017. REUTERS/Issei Kato/File Photo

FUKUOKA/TOKYO, Japan - (Reuters) - A probe into an assault by a sumo grand champion against a junior wrestler threatens to stain the image of Japan's ancient national sport just as its popularity was recovering from previous scandals and a shrinking fan base.

While some wrestlers say the harsh conditions that can breed violence in the closed, hierarchical sumo world have improved in the decade since a teenage wrestler was beaten to death, the new incident shows the path to reform remains a rocky one.