The younger brother's current problem while studying for entrance exams is that he sees his older sister in a sexual way and is unable to study. When her sister pointed this out to her, she took the plunge and begged her for sex...and of course she refused. However, her younger brother doesn't give up and suggests, If your pussy doesn't work, let me lick your anus! She had no choice but to accept her sister's anus, but she gradually became addicted to having her anus licked... without her brother's anus licking her.