|Prototype Model Unit XJ-4|
|Likes||The XJ-Sisters, cleaning/making sure everything is clean, fighting against villains|
|Family|| XJ-1 (younger sister)|
XJ-2 (younger sister)
XJ-3 (younger sister)
XJ-5 (older sister)
XJ-6 (older sister)
XJ-7 (older sister)
XJ-8 (older sister)
XJ-9 (older sister)
|Enemies|| Dr. Locus|
|First appearance||Sibling Tsunami|
|Voiced by:||Kath Soucie|
Appearance and Personality
XJ-4 has a mostly lavender and white color scheme. While she has only one 'leg', which allows her to move with the help of a wheel, she possesses four arms. Each 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 on the left and right of the top of her head, and a longer one in the middle. This longer antenna has a bow tied to the middle of 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 other characters for messes they can't possibly help but create. She has proven to always be there for her sisters, and especially tends to 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 prefer using cleaning utensils instead of weapons
- Jenny calls her a neat freak.
- It's arguably plausible that XJ-4's tube arms concept was incorporated into XJ-9's design.
- Near the end of the episode Turncoats, she asks about 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".