TV-Series
Description
In the anime Ninja Girl & Samurai Master, Azai Nagamasa is introduced as the cocky and opportunistic daimyo of Oumi province. Initially perceived as a man, Nagamasa first appears proposing a political alliance with Oda Nobuna, the series' counterpart to Oda Nobunaga, on the condition that Nobuna marry him. This proposal is eventually refused. Nagamasa later renews the offer to avoid the embarrassment of returning home without an agreement, this time dropping the marriage condition and instead accepting Nobuna's sister, Oichi, as a bride. Unbeknownst to Nagamasa, this Oichi is actually Nobuna's brother, Nobusumi, disguised as a girl.

The most significant revelation about the character occurs later, when it is disclosed that Nagamasa is, in fact, a woman hiding her true gender. This deception stems from a strict father who demanded a male heir to lead the Asai clan. Nagamasa explains that if she had chosen to live as a woman, she would have been sent away as a political hostage to the Rokkaku clan. Faced with this fate, she decided to abandon all feminine habits and assume the role of a man to secure her position and freedom.

Nagamasa's personality is layered and evolves considerably throughout the story. At first, she appears as a calm and manipulative antagonist, driven by a desire for power and self-interest, seeming to enjoy using her charm to manipulate women for political gain. However, this exterior is later revealed to be a facade. She adopted this persona specifically to appear as a "real man" and expresses deep regret for her past attitudes. Despite her claims that love is an obstacle, she longs for genuine affection and accepts her arranged husband relatively easily. Underneath her ambitious exterior lies a deep-seated conflict: she was forced to surrender her identity and personal dreams in exchange for her duty as a clan leader, a sacrifice she eventually comes to regret. She also harbors a strong dislike for war, wishing for peace, and has admitted to hating men due to traumatic experiences in her past.

The character's primary role in the narrative begins as an antagonist and a rival to the protagonist, Yoshiharu Sagara, with the two sharing a mutual disdain for each other. Nagamasa's motivations are rooted in survival and the heavy burden of leadership. Her past includes being captured by the Rokkaku clan and used as a bargaining chip. During this captivity, her mother raised her as a boy to protect her from a dangerous captor. Though she eventually escaped and led a rebellion that freed her clan from Rokkaku control, her father permitted her to rule only on the condition that she permanently discard her female identity. This tragic background forces her to live a lie, believing that a woman in the Sengoku era cannot survive as a leader.

Key relationships define much of Nagamasa's journey. Her relationship with her father, Azai Hisamasa, is extremely strained. He forced her into her male persona and later pressed for an alliance with the Asakura clan against Nagamasa's better judgment, which ultimately led to the downfall of their clan. Her dynamic with Yoshiharu evolves from pure rivalry to a grudging respect, as she acknowledges his ability to devise unusual and creative plans. The most transformative relationship is with Nobusumi, whom she knows as Oichi. After Nobusumi accidentally discovers her true gender, they are married. This relationship allows Nagamasa to experience genuine affection and begin to confront her internal conflict between her duty as "Azai Nagamasa" and her hidden identity.

Nagamasa undergoes significant development as she is torn between her loyalty to her clan and her own feelings. When the Azai-Asakura alliance goes to war with the Oda clan, she is forced to betray her husband unwillingly and fight against those she has come to care for. She is depicted as being torn between these two sides of her life, represented by her male persona, Nagamasa, and her private self, Oichi. In the end, after her father commits seppuku and his final words urge her to let "Azai Nagamasa" die so that "Oichi" can live on, she finally lets go of her male persona. Her death is faked, and she permanently adopts the identity of Oichi, happily joining the Oda clan as Nobusumi's wife.

In terms of abilities, Nagamasa is portrayed as a skilled and capable commander. Before the events of the story, she successfully rebelled against her father to become the head of the Azai clan and later led a successful rebellion against the Rokkaku clan, restoring her clan's glory. While disguised as a man, she effectively used her looks to seduce women in powerful positions to rise to greater political heights, reflecting her cynical view that this was the only way for a woman to survive in that era. On the battlefield, she is a formidable opponent, and her rivalry with Yoshiharu suggests she possesses considerable tactical skill and martial prowess.