My grades haven't been good lately. Seeing me studying hard, my sister immediately encouraged me by promising to listen to any of my requests if I got a perfect score in the next test. Motivated, I didn't leave my desk and studied hard until the day of the test. And as a result, I got a perfect score on not just one but all tests this time. And as promised, my sister will listen to my request. During the three days my parents were away from home, I immediately gave her a "lascivious bunny" outfit to wear. Even though she didn't want to, because she promised, she had to accept. I didn't stop there, I asked her to call me master, stroke my cock, suck my cock, let me fuck her tits and even fuck her! At first it was because of fulfilling the promise, but the feeling of shame when wearing revealing clothes, the feeling of excitement when calling my younger brother master and even letting my younger brother fuck me, these feelings seemed to awaken my anger. Lust inside her body. She took the initiative to want to be fucked by me, to be my "lustful bunny". Three days passed, my parents finally returned home and we went back to normal. But she still promised that, as long as she got a perfect score, she would listen to any of my requests.