Ayumi Endō is a supporting character in the anime Honey Lemon Soda, known for being the first friend the protagonist, Uka Ishimori, makes in high school. Her role as a supportive and outgoing peer is central to her presence in the story.

Ayumi is a high school student whose class placement moves from class B in her first year to class C by her third year. She is characterized by a cheerful, sociable, and warm personality, in stark contrast to the shy and withdrawn Uka. Her friendly and proactive nature drives her to reach out to others, which is how she initiates her friendship with Uka. Physically, Ayumi is depicted as an adolescent female with blonde or yellow hair cut to ear-length and yellow eyes, often dressed in her school uniform.

Her primary motivation within the story is her deep care for her friends. She values Uka Ishimori immensely and sees it as her role to support her, acting as an emotional pillar. This support extends to encouraging the budding romantic relationship between Uka and Kai Miura. When a significant conflict arises regarding a potential school transfer for Uka, Ayumi actively works to persuade Uka's father, demonstrating her dedication and willingness to fight for her friend's happiness.

Ayumi also has her own personal storyline involving her childhood friend, Satoru Seto. She has been in love with Satoru since kindergarten, but her feelings are complicated by his perceived lack of sensitivity and obliviousness to her affection. This unrequited crush causes her worry for a long period. Her own character development culminates during a school camping trip in their second year, where the situation finally resolves and they officially become a couple. Her key relationships, therefore, are defined by her supportive friendship with Uka and her long-term romantic pursuit of Satoru. No notable abilities outside of her social and supportive traits are documented.