Rosa is found talking with Bessie and Erica, in Kathy's Space in Royal Flush Plaza after 8 am on day 2. She and her friends take advantage of the outbreak and are shopping in the line-less stores when they are found by Chuck. They claim that there is a sale and they are not leaving without their box of shoes, which Chuck must carry.
Rosa, Bessie and Erica are some of the survivors that are easily missed due to the 8 survivor limit. This means that if there are more survivors elsewhere, more than 5, they will not show up because Chuck could have more than 8 survivors join him. He must deal with the other survivors so that there is "room" for these 3 by either taking them to the Safe House or killing them.
Rosa shares a similar character model with Gemini Vargas, except that her dress is a different color and her face has different features.
Gemini wore black arm gloves, and since the character model is used for Rosa, the arm gloves have been changed to the color of Rosa's skin, as if she was not wearing gloves. But looking at Rosa's picture, one can see that the gloves are still there, just blended in with the skin.
Rosa is similar to Mindy Baker in Dead Rising, both smiles and look very optimistic.
Rosa, along with Erica and Bessie, does not appear in Off the Record.