Yui being a fighter of the kingdom Kuja she has enough courage and is not afraid to fight even with boys. She looks at the crew members, as brothers, be they animals or even perverted monsters. She proves to be very protective of what they like as Takuya since she does not like him to look for other girls and gets super worried when he is attacked. Yui does not worry about what guys think about it nor stare at her all the time due to her body however she gets embarrassed when Takuya looks at her.