Kintarō Ōe is a twenty-five-year-old man who withdrew from the law department of Tokyo University, the most prestigious university in Japan. He had already completed all the requirements for his degree, but chose to leave because he felt he had nothing more to learn from the academic environment. His primary goal is to study the great university of life itself, believing that true learning should be both stimulating and entertaining. To pursue this mission, he travels across Japan on his trusty mountain bicycle, taking on a wide variety of odd jobs as a temp worker, including positions as a janitor, computer programmer, political campaign staffer, noodle chef, swimming instructor, servant, and animation production assistant.

Kintarō has a tanned complexion with long brown hair tied in a low ponytail and brown eyes. His personal belongings include his bicycle and a notebook he carries on his belt, in which he takes extensive notes on his learning, travels, observations about human behavior, and encounters with women. He also has a notable fetish for toilets, particularly those recently used by beautiful women, though this habit frequently leads to him being caught in embarrassing situations.

On the surface, Kintarō appears to be a perverted, clumsy, and socially awkward individual who frequently launches into elaborate sexual fantasies about the women he meets, often imagining them in dominatrix attire. His behavior is characterized by nervous energy, muttering to himself, exaggerated facial expressions, and lecherous enthusiasm. However, this outward presentation is highly deceptive. Kintarō is in fact a genius-level intellect with extraordinary competence across many fields. He has mastered the entire Tokyo University law curriculum, possesses knowledge of human behavior and psychology, and demonstrates remarkable skill in every job he undertakes. He is also adept in martial arts, though he typically only fights when someone else is in danger or when he becomes genuinely angered; ordinarily, he simply endures beatings without retaliation.

Despite his perverted tendencies, Kintarō is a genuinely kind, empathetic, and thoughtful person at his core. He is excellent with children, encouraging fun and play-based learning rather than harsh discipline. His primary drive is not merely lust but a sincere desire to be of service to others and to learn from every experience. In each of his adventures, he encounters a beautiful woman facing some personal or professional crisis. He initially makes a terrible first impression due to his perverted antics, but through a combination of hidden genius, profound empathy, and extraordinary determination, he ultimately solves her problem and helps her grow as a person. The women invariably come to respect him deeply, and some even fall in love with him, but Kintarō never takes advantage of these feelings, instead completing his research and riding off on his bicycle to his next destination.

A recurring element of his character is the voiceover narration that concludes most episodes, which describes him as being in tip-top physical condition and sparkling mental health, with a hobby of studying the world around him, adding that someday he may be destined to save Japan or even the world, or then again, maybe not. Throughout the series, he demonstrates remarkable physical endurance, surviving falls and fights that would kill an ordinary person. His catchphrase is Study, and he frequently exclaims that things are very educational. His notebook contains comical observations with practical wisdom, such as the fact that the human head cannot turn 360 degrees, which he learned empirically and painfully.