Mongolian wrestler Ama, who posted an impressive 11-4 record at the Autumn Grand Sumo Tournament last month, maintained his top form to win the All-Japan Rikishi Championship on Monday.
Ama beat yokozuna Asashoryu with a leg trip in the semifinals and clinched his first title in the one-day mini tournament by walking Russian Roho out of the ring from behind in the final at Ryogoku Kokugikan.
Ama, who at 115 kg is the lightest sumo wrestler in the top division, is expected to shoot up the rankings at next month's Kyushu Grand Sumo Tournament from the No. 6 maegashira position after winning the Fighting Spirit Prize at the autumn meet.