Masamune did not hand over the family headship to Hidemune, the first son of Masamune with his concubine, the lady of Izaka (a daughter of Izaka clan, commonly called as "Nekogozen," meaning "cat mistress") by determinedly placing Hidemune as an illegitimate child in consideration to the connection of Hidemune with Toyotomi clan.
側室飯坂氏（通称・猫御前）との間に生まれた長男・秀宗はあくまで庶子とみなし、また豊臣家との関係もあったため本家を継がせなかった。