Takeshi Gouda, universally called Gian, is a central and consistently present figure. He possesses a large, strong physique and a quick-tempered, confident demeanor. A defining aspect of his character is his unshakable belief in his own singing ability, which is objectively poor, and he frequently subjects others to impromptu recitals. These performances are sometimes paired with his bad homemade dinners and atrocious fashion sense.

He often appropriates other children's toys and books under the guise of "borrowing" them, a habit that typically casts him as an antagonist. This bullying nature is contrasted by a strong capacity for loyalty and protection; he does not hesitate to assist his friends when they face genuine trouble, a trait often highlighted in feature-length adventures.

His family life significantly influences his behavior. He is terrified of his mother, who runs the local grocery store, a fear others occasionally exploit. He holds a deep affection for his younger sister, Jaiko. Gian also founded and leads his own baseball team, which bears his name. Despite frequently blaming Nobita for the team's losses against its rival, the "Tyranos," he continues to insist on Nobita's participation due to a lack of alternative players.

Certain narratives show his capacity for self-reflection. On one occasion, after no one attended his birthday, he questioned his own lack of popularity. After receiving a lecture from Doraemon about his unruly behavior, he attempted to reform and become a gentler person. This effort was met with mockery from his peers, which ultimately caused him to lose his temper and revert to his previous aggressive conduct.

His role extends into numerous film productions and spin-offs, with the franchise featuring over thirty full-length animated films where his character participates in various adventures.