She is Kukku, a pretty girl in love with Bob.
She is in a good mood because she got to be next to him in the morning!
As for his partner, Bob, well...
He is so absorbed in the train that he doesn't even notice Kukku's presence.
Sometimes Kukku comes rushing toward him and he squeals "beep-beep! to Kukku who sometimes rushes toward him, to show that he can't see the train.
Jiji and Kii, are they quietly watching over their love?
Is it my imagination that the prince who doesn't get along with Bob... looks like he's having a good time?
Alto: "It's fun to see you in trouble, Bob."
Maybe he is thinking?