Jirō Tamiyamaru is the protagonist of the story. His most defining characteristic is an intense, almost obsessive fixation on food and the proper methods of eating. He is not merely someone who enjoys cuisine; he is deeply preoccupied with the "correct" way to consume a dish, agonizing over the specifics of technique and ritual. This obsession places him at the center of the narrative, which comically explores his inability to accept that other people might have different, equally valid approaches to a meal.

Personality-wise, Jirō is portrayed as stubborn and rigid when it comes to his culinary habits. He holds strong convictions about the rules of dining and finds it genuinely difficult to process or respect behaviors that deviate from his own standards. This inflexibility is not born from malice but from a deeply ingrained personal passion, and his resulting confusion and distress over differing eating styles are played for humorous effect. His motivations are not grand or world-altering; rather, he is driven by a sincere, if overly serious, quest to understand and reconcile the gap between his own practices and those of the people around him.

In the story, Jirō's role is to act as the lens through which the series examines the quirky and personal nature of food preferences. His journey is triggered by a simple, relatable dispute with his girlfriend, Mifuyu, over how to properly eat the yolk of a fried egg. This seemingly trivial argument forces him to reflect deeply on his relationships and his own behaviors, opening him up to the idea that different perspectives on food are not wrong, just different. His key relationships are primarily with Mifuyu, his partner, as well as with other supporting characters like Yasuo, Aki, and Chinatsu, who represent varying viewpoints on eating that challenge his own.

Regarding development, the central arc of the story involves Jirō gradually learning to become less rigid. His interactions with others, particularly the conflict with Mifuyu, serve as a catalyst for personal growth, moving him away from agonizing over differences towards a broader acceptance of diverse dining styles. While he does not possess superhuman or fantastical abilities, his notable abilities lie in his hyper-specific knowledge of gastronomy and his intense capacity for analysis when faced with a meal. His entire focus is a humorous exaggeration of the pedantic side of food enthusiasm, making his character a vehicle for exploring the idiosyncrasies of human behavior at the dinner table.