Amami Airi

Fetish: Masturbating (is addicted to it)
Weak spot: Anus

The protagonist's little sister who loves him very much. When she was little, she had a sickly body and she couldn't go out to play like normal children. The protagonist was the only one who played and took care of her, and because of this, she believes her brother is the only man on earth for her from the bottom of her heart. Her brother is undoubtedly the best, an unmatched man and an irreplaceable existence to her.

One night she woke up to the sounds of the protagonist and Mao having sex and masturbated for the first time. Now she has a masturbation addiction, specially anal masturbation using anal thermometers.