As Tenson Ninigi no Mikoto, the grandson of Amaterasu Omikami (the sun goddess) was born by the marriage of Amenooshihomimi (son of Amaterasu) and a daughter of Takamimusubi no Kami, Takamimusubi is equivalent to Tenson Ninigi's maternal grandfather.
天照大神の御子神・アメノオシホミミが高皇産霊神（タカミムスビノカミ）の娘と結婚して生まれたのが天孫ニニギノミコトであるので、タカミムスビは天孫ニニギの外祖父に相当する。