Nobutsuna Matsudaira is a senior retainer and advisor within the Tokugawa shogunate in the alternate-history world of Ōoku: Tanjō - Arikoto・Iemitsu Hen. Based on the historical figure of the same name, he is portrayed as a shrewd, intelligent, and loyal statesman who serves the shogun during a time of great societal upheaval caused by the redface pox epidemic. His background is that of a distant relative of the Tokugawa clan, having been adopted into the family and groomed for high office from a young age. He first served as a page to the third shogun, Tokugawa Iemitsu, and quickly became renowned for his sagacity and political acumen, earning the nickname Izu the Wise. In the story, his primary motivation is the preservation and stability of the Tokugawa regime. He navigates the complex power dynamics of the Ōoku and the broader government with careful calculation, often acting as a voice of reason and strategic counsel. His role is that of a key advisor, supporting the female shogun Iemitsu (Chie) and later helping to guide the transition of power after her death. He maintains close working relationships with other senior officials such as Lady Kasuga and, later, Hoshina Masayuki, and his loyalty is consistently directed toward the shogunate rather than any single individual. Throughout the narrative, his character remains steady and reliable, demonstrating unwavering dedication to duty. His notable abilities include keen strategic thinking, diplomatic skill, and a deep understanding of governance, making him an indispensable pillar of the administration during a period when the traditional gender roles of society have been inverted.