Professor Ichirōbē Hiiragi is Rokuna Hiiragi's eccentric and ambitious father, a scientist driven by the quest for academic recognition and awards. His groundbreaking discovery enables travel between the human world and Mon World, with the goal of bridging both realms. His laboratory operates near the elementary school attended by Rokuna and Mondo.

He invented the Cluckputer, a chicken-based supercomputer that serves as his key research tool, detecting nearby monsters through distinctive chicken noises. This device aids the Mon Colle Knights in locating the six monster items essential for permanently connecting the two worlds. His objective of peaceful coexistence aligns with the protagonists, contrasting sharply with Prince Eccentro's rival team, which seeks the same items for domination.

His intense scientific rivalry with Prince Eccentro fuels their recurring conflicts. While not a combatant himself, Professor Hiiragi's inventions and research provide crucial indirect support to the protagonists. He embodies the energetic, discovery-obsessed traits of a stereotypical mad scientist, primarily motivated by professional accolades. His role remains consistent throughout the series.