Usako Tokugawa, known as Princess Vi or Princess Violet, is the daughter of Emperor Fred (occasionally called Emperor Lei Lei), the nominal but ineffective ruler of Little Tokyo. She functionally controls the city due to her father's incompetence, demanding unquestioning compliance with her wishes. Those failing to meet her expectations or committing minor offenses face immediate repercussions, usually banishment to Prisoner Island—a threat she consistently uses to enforce obedience.

Her tendency toward unauthorized outings during boredom leads to frequent kidnappings by adversaries like Prime Minister Seymour "Big" Cheese. These incidents force the cyborg cat samurai team to rescue her, complicating their operations and directly influencing major plot developments, including enabling villainous opportunities.

In the series' conclusion, she asserts her authority by confronting Big Cheese after his treasury embezzlement is revealed. She terminates his role as Prime Minister and threatens banishment, provoking his escalation into a Colony Drop scheme involving a comet. This confrontation demonstrates her commitment to maintaining political order through severe measures against betrayal.