In 1557, his elder brother, Iekiyo died because of a wound from a battle with Nagayori MATSUNAGA, and Naomasa led the Akai family by acting as guardian for his young nephew, Tadaie AKAI while Naomasa himself lived in Kuroi Castle.
弘治(日本)3年(1557年)、兄家清が三好家の松永長頼との戦いでの傷がもとで死去したため、直正は黒井城に居住したまま幼少の甥赤井忠家を後見して赤井一族を率いた。