Ikeda Tsuneoki, often called Tsune-chan by those close to him, is a central figure in Nobunaga Concerto who serves as the steadfast right-hand man to the protagonist, Saburo, the young man who finds himself thrust into the role of Oda Nobunaga. His background is deeply intertwined with the Oda clan from childhood. He was raised alongside the real Oda Nobunaga, essentially as a foster brother, a unique bond formed because Tsuneoki's own mother served as Nobunaga's wet nurse. This familial closeness, unbound by blood, establishes the profound sense of loyalty and duty that defines his character. In the series, he is depicted as a young man with a ponytail, freckles, and large eyebrows.

Personality-wise, Tsuneoki presents a grounding and often solemn presence that contrasts with the more impulsive and unpredictable nature of the Saburo version of Nobunaga. He is known for his calm courtesy, measured pragmatism, and a quiet but persistent voice of caution. He is not merely a blind follower; his unwavering loyalty prioritizes the welfare of the person he believes to be Nobunaga, and this devotion gives him the conviction to openly voice his apprehensions and even show his anger towards his lord when he believes it is necessary. Rather than being a flaw, this willingness to challenge Saburo in front of others is treated as a testament to the strength and honesty of their bond. He is seen as a paragon of a samurai, a man firm in his beliefs with a caring heart, making him dependable and righteous in the eyes of others. While Saburo might be inconsistent, Tsuneoki is reliable and predictable, the kind of person everyone trusts to make sound judgments.

Motivated above all else by a desire to protect Nobunaga and safeguard his lord's welfare, Tsuneoki spends much of the story as the calm anchor to Saburo's often erratic rule. His role in the narrative is that of a crucial co-protagonist and the primary supporting pillar for Saburo. He is often the one who informs Saburo of critical military and political developments, such as the advance of the Imagawa army, functions as his protector, and provides him with essential knowledge about the era and his own supposed past that Saburo lacks. In many ways, he acts as a bridge between Saburo and the world of the Sengoku period, helping to legitimize the imposter lord in the eyes of other retainers. Tsuneoki's key relationships define his actions and development. His bond with Saburo is the most significant, evolving from a vassal to a lord relationship into a partnership that resembles that of best friends. He is also noted to have a respectful relationship with Kicho, Nobunaga's wife, who recognizes his selflessness.

Throughout the series, Tsuneoki undergoes a significant internal development. While he begins as a staunch defender of the traditional samurai order and the memory of the Nobunaga he grew up with, he eventually comes to a profound realization. He discovers that Saburo is not the real Oda Nobunaga, yet he makes the conscious choice to accept and support him anyway. This decision is a key turning point, moving his loyalty from one based on birthright and history to one based on trust and the merit of Saburo's character and vision. His development lies in learning that the ideal samurai is not just about following rules but about having the wisdom to adapt and the courage to follow the right person, even if that person is an imposter. In terms of notable abilities, Tsuneoki is a capable and dependable warrior, acting as a military commander and protector. However, his most significant abilities are not purely martial. His sound judgment, level-headedness, and unwavering integrity are his greatest assets, allowing him to be a stabilizing force and a moral compass for those around him, especially the often-confused and overwhelmed Saburo.