Gian displays unwavering overconfidence in his notably poor singing and cooking skills, frequently subjecting others to his off-key performances. His favorite food is stuffed capsicum. He captains a local baseball team, "The Giants," and reacts abusively to losses, blaming weaker players like Nobita while prioritizing victory above all.

His family comprises his parents and Jaiko. Gian’s mother operates a grocery store and remains the sole individual he fears; her interventions curtail his bullying. He shares a supportive bond with Jaiko, encouraging her manga-drawing ambitions and occasionally deploying Doraemon’s gadgets to assist her, despite her intermittent frustration with his methods.

Gian’s relationship with Nobita is multifaceted: He relentlessly bullies Nobita, claiming he "can’t eat or sleep" without doing so, yet demonstrates underlying care by rescuing him from danger, providing medicine during illness, or supporting him in critical film moments. Their dynamic occasionally shifts to camaraderie, such as uniting against Suneo. Gian paradoxically depends on Nobita for various tasks despite their antagonism.

In "Stand by Me Doraemon 2," Gian attends adult Nobita’s wedding, singing enthusiastically despite his poor vocals, reinforcing his established traits. His presence remains supportive yet characteristically imposing and unintentionally comedic.

The film does not alter Gian’s core character. His role consistently emphasizes aggression interwoven with sporadic loyalty and familial devotion. Across media, his background and personality remain fixed, solidifying his identity as a bully with occasional redeeming qualities rooted in family bonds and rare friendship.