Polly Ester is a mechanical humanoid cat and the only female member of the Samurai Pizza Cats, serving as one of the main protagonists of the series. In the original Japanese version she is known as Pururun and operates under the codename Nyankee Number Three. She is approximately twenty human years old and works alongside her teammates at the city pizzeria, delivering pizza when she is not fighting the forces of evil.

In terms of personality, Polly is dynamic, independent, and extremely headstrong, with a dangerously short and violent temper. She is often seen bossing her partners around and will readily bully them whenever they say or do something foolish. Although she looks cute and cuddly, she is not very ladylike in behavior and can be fiercely aggressive. Underneath her abrasive exterior, she genuinely cares about her friends, even if she is hesitant to show it. She is also one of the most dedicated and serious members of the team, taking her work both at the restaurant and on the battlefield very seriously, refusing to tolerate slackers and never leaving a task unfinished. She is described as eccentric, temperamental, and the most volatile of the Pizza Cats, yet her temper can be an asset when properly directed. Despite being a fighter, she makes efforts to express her feminine side, such as trying her hand at modeling and singing, because she wants to be taken seriously as a girl.

Her motivations are strongly tied to her belief in the power of love. She fights using love as her central theme, convinced that love and everything associated with it will win out over evil every time. She is also driven by a strong sense of duty to her job and to protecting her city from villainous plots.

Within the story, Polly is a vital member of the three-cat team alongside her leader and teammates. Although the team has a single leader, she is considered just as important as the other members to the group's effectiveness. She has no interest in romantic involvement for much of the series, appearing content to remain single and neither needing nor wanting a man, but in later episodes a secret love for her team leader begins to emerge. This romantic development marks the most notable change in her character over the course of the story, as does the gradual revelation of the caring side she usually hides.

Her combat abilities are distinctive and themed around love and hearts. She plays her beloved pink flute to charm enemies and make them fall in love with her before she strikes them down. She possesses super-sharp claws that can deliver powerful blows, and she throws heart-shaped projectile weapons in battle. Her arsenal also includes a sword with hearts on the handle, which contains a hidden special attack known as the Heart Breaker, as well as a combination of her flute and sword that forms a deadly heart shape. By raising her forearms and making a beckoning cat-like gesture, she can generate a gravitational field that pulls enemies into close range. When angered, she is also known to resort to using a frying pan. Polly wears red armor as part of her usual appearance, and when her armor is removed she is shown to have short red hair and different colored hairbands.