Hikari seems to care for her sister deeply but is not above winding her up just to have her react. While she does care for her sister, Hikari does worry if her relationship with Godou is doing well because she had no experience being with other males before.
Originally, Hikari simply wanted Godou to start a relationship with her sister, Hikari, to not only increase their household strength but to make her sister happy. However, after being rescued from the Monkey King by the hands of Godou, Hikari developed a strong feeling towards him and defend him whenever the girls scold him. By the end of the series, Hikari admits that while she is young, she will wait to become one of Godou concubine just to be close to him.