Azusa Murasaka is a high school student whose family runs a bakery, and she has a younger sister named Misuzu. She has strawberry blonde hair that she almost always keeps tied up, often in a ponytail, using distinctive hair accessories such as a tie with two small white balls. Her eyes are hazel, and her height is 154 centimeters. Azusa has a flexible approach to her school uniform, frequently leaving her jacket unbuttoned, wearing her skirt shorter than average, and sometimes substituting her green school blazer with a more casual jacket. Outside of school, she favors cute and casual outfits like striped shirts, sweaters, and pink shorts, often accessorized with earrings. In the future, her style becomes more mature and trendy, as seen when she wears a black and white polka-dotted overall with a knitted sweater and hoop earrings.

Azusa has a cheerful, playful, and bright personality, often bringing energetic and light-hearted moments to her group of friends. While she can be mischievous and enjoys teasing others, she is also deeply kind and proves to be serious and understanding when a situation demands it. Her willingness to accept nicknames from middle school, such as the Huntsman, shows she is open-minded and comfortable with herself. In the future, she retains her core lively nature but gains a greater sense of maturity and emotional insight. One of her deepest regrets, revealed in an alternate timeline, is that she knew of the mutual feelings between her friends Kakeru Naruse and Naho Takamiya but never spoke up about it.

Azusa plays a key role in the story as a supportive and protective friend, particularly to Naho Takamiya, whom she consistently encourages and defends. She is one of the friends who receives a letter from her future self, which prompts her to join the group's collective effort to change the past and prevent the death of Kakeru Naruse. Her motivation is driven by a genuine care for her friends' well-being and a desire to rectify past regrets. Her ability to balance her playful nature with earnest determination makes her an important emotional anchor for the group. Azusa shares an unbreakable bond with her best friend, Takako Chino, and the two are frequently seen together. She has a famously argumentative yet close dynamic with Saku Hagita, which their friends compare to an old married couple. This bickering relationship eventually develops into dating in the main timeline and marriage in an alternate future. She is also a good friend to Hiroto Suwa and shows deep concern for Kakeru, actively supporting and encouraging him as part of the mission to save him.