You entered the next carriage
You bump into a girl on the train as the door slides open. She apologizes and explains that she is running late to meet her Husband Howl.
You asked her if she knows Vivian
Sophie reveals that she is Vivian's friend and that she came over yesterday to Howl's castle. She gives you a hint.
Sophie: The journey is steep so make sure you have a good walking stick

Ask for directions
Sophie tells you that Howl is in town for the next couple of days and to look for Yato if you get lost on your way. You thank her for your help.