The Girl on the Train is a student who travels on the same train that Hidenori takes to school in the morning.
The Girl on the Train is short and petite, with big brown eyes and dark blue hair in a long ponytail. She is seen wearing her school uniform, which is a white-and-blue sailor fuku with a blue ribbon and blue stripes painted around the sleeves and neck. The most prominent aspect of her appearance to Hidenori is a mole on the left side of her nape, which had a single strand of hair growing from it.
Not much is known of her personality. When her mole hair is pointed out to her, she quickly gets over her initial embarrassment, even beginning to laugh at herself.
In the series
The girl boards the same morning train as Hidenori does, and over time, he comes to notice her and her mole hair. He longs to point it out to her, but lacks the courage, worrying that things will go badly afterwards.
After several days and several missed chances, he finally nerves up and crosses the carriage to stand next to her. However, he gets cold feet again and almost vows to change trains forever to avoid this predicament. Suddenly, he thinks about the situation, and wonders why nobody pointed out the mole hair to the girl despite it being so noticeable. He wonders if there was really no one to point it out for her, and speculates that she might not have many friends.
The train pulls into the girl's stop, and she disembarks. However, a voice calls out to her and she turns around. She sees Hidenori, who has followed her on to the platform and let his train leave. He thinks to himself that he's not just doing this for himself anymore, but for her sake as well. He then tells her directly that there's a hair growing from her mole.
The girl turns red and yelps in embarrassment, covering her neck and looking downwards. Hidenori starts fearing the worst. However, he hears a chuckle, and is taken aback to notice that the girl is actually laughing at her own situation. She then stops and gives him a wide, cheerful smile and thanks him, before leaving. Hidenori later looks back on how foolish he'd been to make a big deal out of the situation.
- The Girl on the Train placed 17th in the character popularity poll, with 1,829 votes.