This was based on the relationship in which because Ujisato had no son of his own, in exchange of presenting Takatoyo with the seven pieces of the family treasure that were handed down for generations by the Rokkaku family, he adopted Takatoyo's son to make him his successor (before this, he received Shigenaga NIWATA, a child of Masazumi NIWATA, to make his successor from the Niwata family which was the Tosho-ke [the hereditary lineage family of Court nobles occupying relatively high ranks] of the same Uda-Genji [the Minamoto clan of the Uda lineage] as he was, and after Shigenaga returned to his parents' home, he tried to get his successor by handing his family treasure over to the Chikuzen Kuroda family and the Tsuwano Kamei family, but in vain.)
これは実子がなかったことから六角家に代々伝わる家宝七品を高豊に贈り、高豊の子を迎えて後継者とした（これ以前には同じ宇多源氏の堂上家である庭田家から庭田雅純の子・庭田重条を迎えて後継者としており、重条が実家に戻った後には筑前黒田家や津和野亀井家に家宝を譲渡し後継者を得ようとしたが、成功していない）縁によるものである。