Takeshi Gouda, widely known by his nickname Gian, is a central figure in his neighborhood, recognized instantly for his large, robust build and his role as the resident bully. The nickname Gian is derived from the English word giant, a direct reference to his imposing physical stature compared to his peers. He typically has tan skin, black hair with a distinctive jagged front cut, and is often dressed in an orange shirt, which has become a signature part of his visual identity. One notable personal feature he is self-conscious about is his protruding belly button.

Gian's personality is a volatile mix of aggression, confidence, and surprising sincerity. He is quick-tempered, loud, and accustomed to getting his way through physical intimidation, earning him the de facto position of leader among the local children. He firmly believes in his own talents, most infamously his singing voice, which he considers excellent despite being objectively terrible and a source of auditory suffering for everyone around him. This lack of self-awareness extends to his cooking, as he forces his friends to eat his horrifying culinary creations, such as the infamous Jaian Stew, often made from bizarre ingredients. Underneath his tough exterior, however, he possesses a strong sense of loyalty and a hidden softness, particularly regarding his family and friends in times of genuine crisis.

His primary motivation in daily life is to assert his dominance, which he accomplishes by taking toys, comic books, and other possessions from other children under the pretext of borrowing them. He derives satisfaction from his hobbies regardless of his lack of skill, forcing his captive audience to attend his concerts or eat his homemade meals. However, a deeper motivation is his desire to be respected and popular, a goal his bullying nature ironically undermines. In rare moments of self-reflection, he has expressed a wish to be a better person, though his attempts at reform are often fragile and quickly undone by frustration or mockery from his peers. His greatest and most effective motivation is his fear of his mother, who runs the local grocery store and is the only person who can consistently discipline and terrify him.

Within the story, Gian serves as an antagonist and a primary source of conflict in the everyday lives of Nobita and his friends. Many episodes revolve around their elaborate schemes to avoid his bullying, his singing recitals, or his birthday party. He is the captain and founder of the neighborhood baseball team, which he named after himself, the Giants. Despite the team frequently losing due to the poor performance of members like Nobita and Suneo, Gian forces them to continue playing, often using his fists as motivation. Conversely, in the long-form adventure movies, Gian undergoes a significant shift, transforming into a courageous and reliable ally. In these stories, he is often the first to stand up against a real villain, protects his friends at great personal risk, and shows a heroic sense of justice that is less visible in the everyday episodes.

Gian's key relationships define much of his behavior. He is often seen with Suneo Honekawa, who acts as his fawning sidekick, though Gian frequently bullies him as well. His primary target is Nobita Nobi, whom he torments constantly, often for no reason other than to vent his own frustrations. However, this dynamic is complex, as Gian has shown he will not allow others to bully Nobita and has expressed a hidden, prideful desire to be his true friend. He treats Shizuka Minamoto with more respect because she is a girl, though he still subjects her to his concerts and cooking. His most defining positive relationship is with his younger sister, Jaiko, whom he adores and protects fiercely, often going to great lengths to support her dream of becoming a manga artist.

While Gian does not possess magical abilities, his notable skills are entirely physical and social. He is the strongest and most athletically talented child in his group, making him a formidable opponent in a fight and a powerful asset to his baseball team. His singing voice, while dreadful, is so powerful it can be used as a weapon, causing pain and even physical incapacitation to those who hear it. Over the course of the series, his character shows a subtle but meaningful development. Although he rarely changes his bullying ways in the short stories, the many adventures he shares with his friends reveal a growing sense of responsibility and courage. He learns to channel his strength towards protecting others in dangerous situations, suggesting that his aggressive nature masks a deep-seated capacity for heroism and loyalty.