Akebono, the first foreign-born sumo wrestler to become a grand champion, has died aged 54, US officials and Japanese media said Thursday.
Born Chad Rowan in Hawaii in 1969, Akebono was among the most successful sumo wrestlers of the 1990s.
Akebono was named the 64th yokozuna, or grand champion, in 1993 and became a Japanese citizen in 1996.
Kyodo News agency said he died in early April and had heart failure.
US Ambassador Rahm Emanuel called Akebono "a proud Hawaiian and a bridge between the United States and Japan".
"When Akebono became the first-ever foreign-born grand champion, sumo's highest rank, in 1993, he opened the door for other foreign wrestlers to find success in the sport," Emanuel said in a statement.
"Throughout his 35 years in Japan, Akebono strengthened the cultural ties between the United States and his adopted homeland by uniting us all through sport."
Standing more than two metres (6ft 5ins) and weighing over 230 kilos (510 pounds), Akebono was best known for his fierce competitions with local favourites Takanohana and Wakanohana, who were born to an elite sumo family.
He featured prominently at the opening ceremony of the 1998 Nagano Winter Olympics.
He retired as a wrestler in 2001 to train younger fighters and later did other martial arts as well as professional wrestling.