Sasaki

Sasaki is the male protagonist. He is a tired middle-aged businessman working in sales, which is often a demanding and draining job (which Tayama calls a "black company"), who is refreshed by going to Yamada's checkout to make his purchases because of her friendly customer service and nature.

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He doesn't recognize that his favorite employee, Yamada, is the same as his new smoking friend Tayama.

(Source: Wikipedia)