Reina, the disciplined Student Council President, struggles to manage her non-blood-related younger brother, Shouta, whose obsessive "sister complex" leads to constant harassment. Despite her efforts to maintain order while their parents are abroad, Reina eventually succumbs to Shouta's manipulations and her own hidden desires, agreeing to become his devoted "pet." Their forbidden relationship reaches a breaking point when Aina, the younger sister, unexpectedly returns home to find them together.
After months of spying on the secret relationship between Shouta and their older sister Reina, Aina decides she wants the same pleasure for herself. She sneaks into Shouta's room and begs to become his "pet," leading to an intense night of initiation. Now fully corrupted, Aina enters a competitive rivalry with Reina to see who can be the most devoted and lewd servant to their brother.
Shota continues to dominate his sisters, Rena and Aina, treating them as his personal pets. When the sisters attempt to use an aphrodisiac to bind Shota to them exclusively, he outsmarts them by drugging them instead. Shota decides to escalate their training, transforming them from pets into obedient "livestock." After a period of intense conditioning and submission, both sisters fully embrace their roles as his slaves, eventually becoming pregnant with his children.
Shota continues to dominate Rena and Aina, who attempt to secure his exclusive affection by drugging him with an aphrodisiac. However, Shota outsmarts them, turning the tables to further break their will and "tame" them as livestock rather than mere pets. After fully submitting to his control, the sisters embrace their new roles, culminating in Rena's revelation that she is pregnant.
Oura-sensei's perception of his "angelic" student, Amiya, is shattered when he finds a diary suggesting she is a schoolgirl prostitute. However, Amiya uses his shock to manipulate and blackmail him into a sexual encounter, eventually revealing that the diary was merely a prank to get the oblivious teacher's attention. The two succumb to their desires and begin a secret, passionate relationship.
Oura-sensei's perception of his "angelic" student, Amiya, is shattered when he discovers an agenda suggesting she is a schoolgirl prostitute. However, Amiya reveals the entries were a prank designed to provoke the naive teacher, leading her to manipulate and seduce him. After a night of passion, the two enter into a secret relationship where the student now holds the power over her teacher.