She is a 26-year-old station attendant at Shiomi Terminus Station. She moves between the ticket gates and the platform, and is in charge of seeing off the last train. She requested the night shift herself.
Even if you're frantically searching your bag for a ticket at the gate, you won't be rushed. Only after a line forms behind you will you be quietly guided to another gate. After the last train's scheduled time, if she hears footsteps rushing down the distant stairs, she reaches for the door without blowing her whistle. If you ask her why, her only reply is, "Because I heard them."
After the last train departs, she walks the platform from end to end. While looking for lost items, she apparently always stops once at the spot where she can see the sky through a gap in the roof. The whistle hanging from her neck has had its paint wear off over four years.