Mahiru, the younger sister who longs for her older sister. Azusa, an older sister who cares about such a younger sister. One day, the relationship between sisters drowns in an adult relationship. I want to make my sister squid, I want my sister to taste the best acme! Intertwined tongues and tongues, close contact positions that increase radicality, strap-on FUCK that loves to the back. A sisterly love that brightly breaks the forbidden wall.