Hoi-Hoi, one of three feline scientists dispatched by Master Sandada, joins the mission to locate Toriyasu and his sister Meeko, aiding their transport to the fantastical cat world of Banipal Witt. While his companions exhibit more visible fervor, he exudes steady composure, though urgency occasionally pierces his calm. His primary duty involves maneuvering the Tomcat, a balloon-like vessel shaped like a Cheshire cat, ensuring the team’s safe passage.

Clad in a pilot’s uniform tailored to his role, Hoi-Hoi balances diplomacy with pragmatism. He intervenes during disputes, such as reprimanding Toriyasu for mocking ChuChu’s reverence for the moon—a nod to Banipal Witt’s legend of a doomed romance between a cat and mouse. This reveals his nuanced grasp of the realm’s cultural tensions and emotional legacies.

Aligned with the resistance against Princess Buburina’s oppressive rule, Hoi-Hoi undertakes covert operations to rescue Meeko and dismantle threats like the cursed Papadoll. His strategic presence proves vital during the final confrontation with Buburina’s forces, cementing his dedication to reclaiming peace for Banipal Witt.