Misumi Rei (YSN-653) is being raised by a useless older brother whose mind is only focused on sex.

Rei is the younger sister who is used as a sex-crazed tool by her good-for-nothing older brother, whose mind is only filled with sex. Although she is interested in sex, she always feels a little unmotivated when the other person is her older brother. However, when a hard penis is inserted into her, she naturally shows a maternal expression and sways her hips while making love. What an adorable younger sister.