From what I see here, it appears that she died to a train accident awhile ago and the other one is just remembering her? I found it strange with all the train references and the fact that the Cafe girl didn’t address her friend so I assume she died in a train accident

I'm not so sure since she's drinking a cup as well. I think the Cafe girl was just fangirl-ing too much to notice. I figured she just disappeared to get an umbrella.