"Let big sister take care of it! Just this once, you can rely on me completely. I'll do anything for you—I only have one little brother in this world◆" Seduced by my sister's erotic advances, my rational mind gradually wavers and finally shatters. "Straight-chan, you haven't been satisfying your desires, have you?" She pulls me into her arms, whispering tender yet commanding, sweet words that draw me deeper. Lost in a dreamlike state, my heart and body slowly become one with hers. Under my sister's abnormal seduction, there's no turning back for me anymore.