11-year-old Estelle never imagined she'd be sold off by her own mother. But the buyer is the one and only duke in the empire, Ein Castielo... and he's Estelle's father?! Feared across kingdoms for his blood-red eyes and the immense powers of his magical lineage, Ein is the cold master of House Castielo. His sworn enemies and dashing knights could become Estelle's, but does being his rare daughter really mean she is a child of this house?