Tayama, or Yamada, is a neat and cheerful supermarket cashier who, overwhelmed by daily stress, transforms into a cool punk girl outside of work to secretly smoke and unwind in a hidden spot behind the store.

There, she meets "Sasaki," a middle-aged regular customer, and they become after-work smoking buddies and chatting partners—all without Sasaki realizing that Tayama and the Yamada who greets him at the storefront are the same person.

Although she acts tough, rugged, and straightforward in her Tayama persona, she is actually very shy and secretly has feelings for Sasaki. Because of this, she constantly has to juggle her dual identities, put on a stoic facade to keep her true identity a secret, and hide her blushing embarrassment whenever she is close to him.