Ibara serves as the primary antagonist in the Treasure Island arc of Dr. Stone: New World, acting as the manipulative prime minister of the island's Petrification Kingdom. He is an extremely tall, elderly-looking man whose physical design, with gaunt features and a hunched posture, visually signals his cunning and sinister nature even before his actions speak for themselves.

In terms of personality, Ibara is defined by his merciless, manipulative, and profoundly arrogant nature. He is acutely aware of his own cleverness, a trait that leads him to consistently overestimate his strategic abilities while underestimating everyone around him, particularly those from the Kingdom of Science. This hubris is his defining weakness; he cannot fathom the existence of individuals with photographic memories or exceptional crafting skills, nor can he predict the advancements of science, which he perceives as a form of magic. Beyond his cunning, Ibara displays a cruel and perverse demeanor, maintaining a harem and showing no regard for the safety or loyalty of his followers. He rules through fear and deception, having fooled the islanders for years by claiming to communicate with a deceased Great Leader whose statue he secretly shattered.

Ibara's motivations are rooted purely in a selfish desire for power, control, and pleasure. Years before the main events, he seized the powerful petrification device known as Medusa, using it to petrify and effectively kill the island's true Great Leader before usurping leadership. His primary goal throughout the New World arc is to maintain this iron grip on Treasure Island by any means necessary, including sacrificing his own troops and petrifying the entire population to eliminate the threat posed by Senku and his friends. He operates from a position of paranoia, constantly seeking out infiltrators and eliminating anyone who discovers the truth about his rule.

As the power behind the throne, Ibara's central role in the story is to act as the final obstacle for the Kingdom of Science during their mission to obtain the petrification device. Unlike previous antagonists, Ibara has no scientific knowledge but compensates with a brutally pragmatic and strategic mind, allowing him to counter many of Senku's initial plans. Key relationships define his role as a villain. He has no true allies, only subordinates like Kirisame and Moz whom he manipulates and discards when they are no longer useful. His most significant relationship is his adversarial dynamic with Senku, which is framed as a direct contrast: Senku draws people in with trust and science, while Ibara betrays and rules through fear and isolation. He also shares a crucial connection with Soyuz, the son of the true Great Leader; Ibara had attempted to murder Soyuz as an infant and unknowingly spends the arc opposing the rightful heir to the island.

Throughout the narrative, Ibara demonstrates little to no character development, remaining a static and irredeemably evil force. His role is to be a villain who cannot be reasoned with, forcing Senku to confront a purely selfish and destructive ideology in a high-stakes battle of wits. His defeat comes not from a change of heart but from the culmination of his flaws: his cowardice, his lack of trust in others, and his inability to understand the power of cooperation and sacrifice, which ultimately leads to his own petrification.

Regarding notable abilities, Ibara lacks scientific expertise but is exceptionally cunning and paranoid. He is a skilled strategist, able to devise brutal plans such as shattering the Master's statue to eliminate a potential political threat and activating the Medusa to petrify the entire island. He also possesses considerable physical strength for his aged appearance, capable of fatally wounding opponents with his sharp nails. However, his most significant asset is the Medusa, a powerful petrification weapon he wields to maintain control, though his understanding of its complex command system is limited.