Jirō Tamiyamaru serves as the central protagonist throughout all official media. His defining trait is an intense fixation on the precise methods of food consumption, extending beyond typical interest into significant personal preoccupation.

This obsession manifests as profound distress over perceived "correct" dining techniques, with the specific timing of breaking fried egg yolks becoming a recurring focal point. He experiences notable discomfort and comedic tension when encountering others whose eating habits diverge from his rigid standards.

The narrative consistently places him within varied dining scenarios where his meticulous focus on consumption rituals overshadows both social interaction and culinary appreciation. His interactions frequently involve conflict, internal or external, stemming directly from these differing approaches to food.

Information regarding his family background, occupation, education, or life experiences outside his relationship with food remains absent. Similarly, no significant evolution, growth, or change occurs in this core trait across the series or any related media.

The character maintains this singular focus on eating methodologies across all appearances. No spin-offs, movies, OVAs, or alternative media expand his role or backstory beyond this established pattern.