悠木 圭太

The protagonist of the story. He is a second grade high school student. His mother died a few years ago, so he has to take care of his little sisters. His father is an archeologist, so he is rarely home because he has to fly around the world. Keita is in charge of the housework and household. 

He is happy that his little sisters grow up day by day; however, he also feels desire towards them. "My cute little sisters, I want to make them only mine." Even though he knows that it is impossible, he doesn't give up his dream. He sneaks in to his little sisters' bedrooms at night and masturbates while looking at their sleeping faces.