In 1939, Genichi KOIZUMI pointed out the similarity with Osakura in Jeju, of the Republic of Korea, and advocated a theory that regarded Jeju as the place of spontaneous growth and origin, but since there is no extant pressed flower specimen, which is said to have been used by Koizumi to compare Someiyoshino and Osakura, this theory has been doubted since the beginning.
1939年に小泉源一が大韓民国の済州島の王桜との類似を指摘して、済州島が自生地であり起源とする説を唱えたが、小泉がソメイヨシノと王桜との比較に用いたとされる押し葉標本が残されておらず、当初からこの説は疑問視されていた。