Akane Tendo is the youngest of the three Tendo sisters and a central figure in the story. As the primary heir to her father Soun Tendo's Anything Goes Martial Arts dojo, she is a skilled martial artist in her own right, though her technical proficiency is often overshadowed by the extraordinary abilities of those around her. Her mother passed away when Akane was very young, which contributed to her not learning many traditional domestic skills, and her notoriously poor cooking is a recurring aspect of her daily life. She grew up as a tomboy, frequently getting into fights and dedicating herself to martial arts from an early age.

Akane's personality is defined by a sharp duality. On one hand, she is fundamentally kind, friendly, and compassionate, often going out of her way to help others, even those who are her rivals. She has a strong sense of personal honor and disapproves of attacking anyone who cannot defend themselves. On the other hand, she possesses a famously fiery temper and a stubborn, relentless nature. She is deeply insecure about her attractiveness, her level of skill, and her lack of traditional feminine talents. These insecurities frequently manifest as explosive jealousy and anger, most often directed at her fiancé, Ranma Saotome. She is quick to resort to physical violence using whatever blunt object is nearby, though she is also quick to feel remorse and apologize once she has calmed down. Despite her tough exterior, she has very traditional feminine fears, such as a fear of ghosts and reptiles, and she has a deep-seated need for comfort when sad or scared.

Akane's primary motivation throughout the story is to reconcile her identity as a strong martial artist with her desire to be seen as a desirable girl. Initially, she had a crush on the family doctor, Tofu Ono, and grew her hair long in an attempt to appear more feminine for him. After her hair was accidentally cut short, Ranma comforted her by saying she looked cute, which helped her begin to move past that crush and develop feelings for him. Despite their constant bickering and her frequent claims of hating boys, she is deeply devoted to Ranma. She consistently worries about his safety, cheers him on in fights, and repeatedly risks her own life to save him, even when he is being insensitive or insulting. Her jealousy is most pronounced when she sees him with his other numerous fiancées, like Shampoo and Ukyo Kuonji, which triggers her possessive nature.

In the specific story "Nightmare! Incense of Spring Sleep", Akane becomes the accidental victim of a magical incense created by the lecherous martial arts master Happosai. The incense was intended to put Ranma to sleep for the entire spring as revenge, but Akane inhales it instead. The incense's effect is unusual: while it puts the user into a deep slumber, it also allows them to automatically and violently defend themselves from any threat. However, because the incense was used during a time of peace rather than in a dangerous situation, it causes the user to go on an uncontrollable rampage. While unconscious, Akane begins to act out her vivid dreams in the real world. For instance, when she dreams of Ranma two-timing her with Shampoo and Ukyo, her sleeping body physically attacks him. The dream sequences induced by the incense reveal her underlying anxieties, showing that she has a slight fear of Ranma's other fiancées, Kodachi, Ukyo, and Shampoo, although this may be an exaggerated side effect of the incense.

Her most significant relationship is with her fiancé, Ranma Saotome. Their engagement was arranged by their fathers to ensure the future of the Tendo dojo, but their relationship is a chaotic mix of genuine affection, constant insults, and physical comedy. They bicker endlessly, with Ranma calling her "uncute" and Akane calling him a "pervert," yet they are almost always seen together and work effectively as a team when the situation demands it. Akane also has a close, if sometimes exasperated, relationship with her two older sisters. She looks up to her eldest sister, Kasumi, as a surrogate mother figure and role model for femininity. Her middle sister, Nabiki, is often a source of financial manipulation and teasing. Akane is also adored by several other male characters, including the kendoist Tatewaki Kuno and the lost boy Ryoga Hibiki, though she is largely oblivious to the latter's true feelings. Unbeknownst to her, Ryoga's cursed form as a small black pig named P-chan often sleeps in her bed, which is a source of immense frustration for Ranma.

While Akane does not undergo a drastic personality overhaul, she shows clear development throughout her story. She becomes less insecure about her short hair and begins to accept her tomboyish nature. Her feelings for Ranma evolve from irritation and denial to a deep, if unspoken, love. By the end, she proudly declares Ranma as her fiancé and is ready to marry him, having moved past her initial reluctance regarding their arranged engagement.

Regarding her abilities, Akane is a formidable martial artist, though not on the same superhuman level as Ranma or his primary rivals. Her true strength often manifests when she is enraged or loses control. She is athletic and excels in various school sports, serving as the captain of her school's volleyball team. She has demonstrated skill in multiple combat situations, including fighting off hordes of male suitors every morning, holding her own in a kendo match against Tatewaki Kuno, and navigating the heads of a giant dragon. Despite her combat prowess, she has notable weaknesses, including an inability to swim and a complete lack of culinary skill.