The Japan Sumo Association officially approved Mongolian wrestler Hoshoryu's promotion to yokozuna, the sport's highest rank, at an extraordinary board meeting Wednesday.The 25-year-old grappler won the New Year Grand Sumo Tournament in a three-way championship tiebreaker Sunday at Tokyo's Ryogoku Kokugikan arena after finishing as joint leader with a 12-3 record."I will continue to work hard with a strong determination in order not to tarnish the title of yokozuna," Hoshoryu said during a promotion ceremony at his Tatsunami stable in Tokyo after the JSA meeting.He becomes the sport's 74th …READ FULL ARTICLE