A) If we use as our base the premise that Miyagi's successor should be the oldest active student, who has the appropriate experience until the day of his death, desire to serve others and with sufficient teaching skills, then it would be necessary to decide (in Okinawa) between Seiko Kina, Iha Koshin, Yagi Meitoku, Higa Seko and Miyazato Ei'Ichi. Outside Okinawa the sole candidate would be Yamaguchi Gogen Sensei, who in 1930 had founded a dojo in Kyoto for the practice of Goju ryu, and since then had not stopped teaching this style of karate which was working (Manchuria, Mongolia, Kagoshima, Tokyo, etc.). Unfortunately Okinawan official records were destroyed during the Second World War and have no trustworthy information at hand about which one had in those years a real student body with enough organizational structure to enforce their desires to direct the future of Goju ryu in the ideals of Miyagi sensei, and was also certified as such by some government agency or government office as the Dai Nippon Butokukai in Okinawa, was closed by the U.S. and allies after the WW II.
B) Starting from the premise that Miyagi's successor should be the one who had acted as his assistant longer time after the Second World War (being from those years when it expanded worldwide on Goju Ryu), which also was considered in charge of the Miyagi's dojo for over three years and also by many of the older students, close to the daily life of Miyagi sensei... that successor would be Miyazato Ei'Ichi sensei.
C) Based on the reputation, development and expansion given to Goju Ryu in Japan, Okinawa and the west, after World War II, we should choose the successor of Miyagi Chojun from: Yamaguchi Gogen (Japanese Goju Ryu), Toguchi Seikichi (Shoreikan), Yagi Meitoku (Meibukan) and / or Miyazato Ei'Ichi (Jundokan). D) If we take the hypothetical case (but not impossible) that Miyagi Chojun sensei had decided to transfer all his secrets, and left as heir to his style of karate, his latest and younger uchideshi, almost 23 years of age when Miyagi died, and just about five years of practice, then the heir of Okinawa Goju ryu karate-do would be Miyagi An'ichi. by Takayoshi Sichiyama Alvarez (Takayoshi Sakamoto)