Appearance and Personality
XJ-4 has a mostly lavender and white color scheme. While she has only one leg-like appendage, which allows her to move with the help of a wheel, she possesses four long robotic arms. Each arm has two fingers, and these arms aid in her goal to retain neatness, as she can grabbily multitask quite well with them. She has three antennae; two short ones protruding from either side of her head, and a longer one sticking up from the middle. Her long middle antenna has a lavender bow tied around it.
Built assumingly for cleaning and multitasking, XJ-4 is incredibly devoted to making sure everything is perfectly clean, even to the point of chiding others for messes they can't possibly help but create. Despite her obsession with cleanliness, she has proven to always be there for her sisters, and especially tends to the youngest baby sister, XJ-1.
XJ-4 can produce many, perhaps all, types of cleaning utensils and products. Along with this, she can also work with the other XJ Series robots to create various structures and weapons. She sometimes prefers to use cleaning utensils in place of weapons.
- Near the end of the episode Turncoats, while Dr. Wakeman is repairing her and her sisters, XJ-4 asks if she'll have the ability to spray Scrubbing Bubbles. This is a reference to the trademark bathroom cleaner.
- She is the oddball of her sisters in terms of her overall design as XJ-1 to 3 and 5 to 9 follow a similar design scheme: A blue/aquamarine & white color pattern, pigtails, and/or an upper body consisting of a "tank top and a mini-skirt".
- She is the only member of the XJ series besides Jenny to have a visible moving mouth.