Ichigo Aika: Zatsu de Namaiki na Imouto to Warikirenai Ani

Synopsis...

His new stepsister is a super sassy and foul-mouthed person who only behaves in front of their parents but is uncontrollable while their parents are away. This makes Kota’s life a living hell, and a terrible relationship unfolds, with the two hurling insults at each other whenever they meet. However, their relationship begins to change when Aika gradually warms up to Kota’s caring older-brother nature.