His stepmother, Moriko (though aged 11), adopted Motomichi, serving as his conservator when she was awarded Jusango (a title awarded to Imperial family members, nobles, and ministers for their meticulous services) and became the Junbo (the stepmother of an emperor) of Emperor Takakura in the following year.
継母（といっても11歳）の盛子が翌年准三后を賜り高倉天皇の准母（白河殿）となると、盛子は基通を自らの養子としてこれを後見した。