In this film the main characters are Satsuki(10) and Mei(4), the children with their father moved to rural japan to closer to there mother of long term illness. Right from the start when dads working at home and Satsuki is at school, Mei goes off into this forest thicket, where she meets Totoro a forest god, and starts playing on top his belly when he tries to sleep. You may have seen this scene from southpark with Cartman and kuthulu, I usually like southpark but that episode annoyed making fun of a great movie like this.
Throughout the movie her and her sister meet up with Totoro. Satsuki First meeting is when shes holding Mei waiting at the bus for her father in the rain. Totoro takes them into a cat bus and have an adventurous ride, until they meet up with father. As you see in the above picture, they meet up again late one night while Mei is impatiently waiting for there garden to grow, Totoro takes the girls to dance around the garden and make them magically grow. The very next day they weren't huge like last night but they finally sprouted.
This movie takes you back to your childhood, with beautiful art, funny situations and even back to a child's love of their mom when there in the hospital. If you have seen spirited away, or Ponyo, or even Valley of the Wind you will love this, i'll be talking about those other movies soon, I definitely suggest collecting all of Miyazaki's movies.