Yes — foreign wrestlers have competed at the highest levels of sumo for decades, though participation is regulated and sometimes contentious.
Current rules: Each stable may have a maximum of one foreign-born wrestler. This rule, introduced in 1992 after concerns about Mongolian dominance, limits the total number of international wrestlers in the professional system. Foreign wrestlers must receive a Japanese visa status tied to their stable and must live in Japan year-round.
Historical waves of foreign wrestlers: The first notable international wrestler was Hawaiian-born Takamiyama (1964). Other Hawaiians followed — Akebono and Musashimaru became Yokozuna in the 1990s. Then came the Mongolian era: six Yokozuna from Mongolia, including the legendary Hakuho (greatest of all time with 45 tournament victories) and current Yokozuna Hoshoryu.
Today's international wrestlers: The current Makuuchi division includes wrestlers from Mongolia, Ukraine (Aonishiki and Shishi), Russia, Georgia, and other countries. Ukrainian-born Aonishiki is the fastest-rising foreigner in modern sumo history, reaching Ozeki in just 14 tournaments.
Limitations after career: Foreign-born wrestlers cannot obtain the 'elder names' required to remain in sumo as coaches or stable masters unless they acquire Japanese citizenship. This has caused notable wrestlers like Hakuho (now naturalized Japanese as Miyagino) to navigate complex processes.