Yamada is an employee of the supermarket known as Super S. She initially started in a part-time position 8 years ago as a teenager.

Spoiler

As Yamada, she is a cheerful, flawless customer handler. Her real self, which she introduces to Sasaki as "Tayama", is much more frank and less outwardly polite. She invites Sasaki to come to the smoking area behind the store, which he then does regularly.