Asuka Tokugawa is a central character in the anime E's Otherwise. She is a young adolescent girl who becomes the de facto leader of the Dragoons, a group of psychics rebelling against the powerful organization ASHURUM. Her driving motivation is a deep-seated desire for revenge against ASHURUM, stemming from traumatic experiences where she was captured and subjected to their experiments.

In her daily life, Asuka is depicted as a kind and compassionate individual with a strong sense of empathy. She has a particular fondness for animals and is often seen taking care of stray creatures. This gentle nature contrasts sharply with her role as an adversary, highlighting the personal cost of the conflict. Her helpful personality extends to household chores, although she is notably terrible at cooking, a trait that is played for humor. Despite her best efforts, her skills in the kitchen are notoriously poor.

A significant relationship in her life is with Yuuki Tokugawa. Although Yuuki treats her as a younger sister, Asuka is, in fact, the older sister. As orphans who lost their parents to ASHURUM's attacks, Yuuki found Asuka wandering the streets of Gald and took her in, creating a strong but complicated foster sibling bond. Her unexpressed romantic feelings for the protagonist, Kai Kudou, represent a more tender and unfulfilled aspect of her personality. Her affection for him remains a delicate bud that never fully blossoms, much like her latent psychic potential.

While her primary role in the story is that of an antagonist leading the Dragoons against ASHURUM, her development reveals a character shaped by trauma and a desire to fight back against the forces that harmed her and others. Her notable abilities are psychic in nature. She is capable of sensing the emotions of both people and animals, a power that aligns with her naturally empathetic disposition. Although her full psi abilities are not always on display, they become significantly more apparent and powerful when large waves of psychic energy are unleashed.