There needs to be a version of this with other characters waiting for the train with Youmu.

It would also be nice if the train were large enough for her to fit inside.

Foreshortening. Trains are notoriously hard to judge the distance / size / direction of, so it's very much in line with the physical reality.

http://img101.imageshack.us/img101/1579/smalltrainnk4.png

Depending on how large the gap between the platform and the train is, the top edge of the door would be in the middle of Youmu's forehead, or level with the crown of her head. She'd have to stoop to get onto the train, and she's a little girl!
That's not how it works in my physical reality.

LaC said:
http://img101.imageshack.us/img101/1579/smalltrainnk4.png

Depending on how large the gap between the platform and the train is, the top edge of the door would be in the middle of Youmu's forehead, or level with the crown of her head. She'd have to stoop to get onto the train, and she's a little girl!
That's not how it works in my physical reality.

I'm half tempted to send xexu that picture.