On the original poster as well as on the DVD and Blu-ray cover, there is a mysterious girl standing next to Totoro. She isn’t Satsuki or Mei, and this girl does not appear in the movie. Yet, here she is.
Below is the scene that appears in My Neighbor Totoro, with both sisters standing next to furry giant.
Here is the official art, which is still used.
The girl does look like a combination of Satsuki and Mei, which might explain who the girl is. She’s not Satsuki, nor is she Mei—she’s both. But according to website Poster Pagoda, there might be a better reason.
During the mid-1970s, Hayao Miyazaki began coming up for concept art for what would become My Neighbor Totoro. The early art featured Totoro and a seven-year-old girl, but as Miyazaki fleshed out the idea, he decided that two girls would better tell the story.
“If she was a little girl who plays around in the yard, she wouldn’t be meeting her father at a bus stop, so we had to come up with two girls instead,” Miyzaki said in The Art of My Neighbor Totoro. “And that was difficult. Her first encounter [with Totoro] at the bus stop seemed so perfect.”
The result was two girls: four-year-old Mei and 11-year-old Satsuki.
The “rainy day encounter” in its original form must have resonated with Miyazaki so strongly that he felt it was the best way to promote the movie.