She is portrayed by Lucy Chappell.
Rosa and her family meet Albert Einstein, as he is to stay at their home in Aarau, Switzerland until he finishes his studies. She also participates in her family's debates at dinner and encourages Albert to join in on the conversation.
When Albert passes his entrance exam for Zurich Polytechnic, Rosa and the Winteler family say their farewells to him.
Rosa joins with her family, as well as Albert, Maja, and Albert's friend Michele Besso, as they celebtrate her sister Marie's birthday. Rosa listens as her father Jost celebrates Albert and his sister for being so close to family, thanks Albert for bringing Michele over, hoping for him to come to more dinners in the future, and thanks Albert for his companionship with Marie.
Later, Rosa and her siblings say good bye to Albert and Michele as they go back to Zurich.