Ayasa Tachibana is a high school student and a highly skilled beach volleyball player who serves as both a mentor and a primary rival to the protagonists in Harukana Receive. She is best known as the calm and perceptive partner of Narumi Tooi, forming one of the most formidable pairs in the series.

Ayasa initially comes from an indoor volleyball background, having earned a scholarship for the sport. Her path changed when she witnessed Narumi Tooi spiking a beach volleyball with unexpected force. Intrigued by the power and technique Narumi displayed despite her stature and the different nature of the ball, Ayasa became captivated by beach volleyball. Her interest ran so deep that she made the significant decision to forego her indoor volleyball scholarship entirely in order to become Narumi's partner. To demonstrate her commitment, she made a bold vow to drop out of school if they did not win the high school volleyball tournament together.

In terms of personality, Ayasa is characterized by her quiet, understanding, and perceptive nature. She is notably mature and level-headed, often acting as a grounding presence for her more intense partner, Narumi. This understanding extends to her rivals as well; she is observant of others' feelings and the history between her partner and Kanata Higa. Demonstrating a strong sense of sportsmanship, Ayasa once pulled Haruka Oozora aside to gently warn her about Kanata's past struggles with volleyball partnerships, advising her to be cautious. She also went out of her way to give Haruka, a potential competitor, helpful tips and her phone number, saying she was available anytime.

Ayasa's primary role in the story is that of a goalpost for the main characters, Haruka and Kanata. As a pair, she and Narumi are depicted as the defending champions and a near-insurmountable wall that the protagonists must work to overcome. Her role also includes providing early inspiration and guidance to Haruka, as it is her and Narumi's practice that first sparks Haruka's fascination with the sport. In the manga's narrative, the central promise and long-term objective for Haruka and Kanata is to face and defeat Ayasa and Narumi in a formal tournament.

The most defining relationship in Ayasa's life is with her partner, Narumi Tooi. Their bond is one of deep trust and mutual dedication, forged from Ayasa's decision to completely change her athletic career to play alongside Narumi. Ayasa seems to accept that Narumi still carries emotional baggage from how things ended with her previous partner, Kanata, and supports her through it. Her other significant relationship is with the main protagonist, Haruka Oozora, whom she treats with a mixture of respect and guidance, seeing her as a promising newcomer and a rival worth helping.

While Ayasa is not a central point-of-view character and is considered one of the less developed characters in the anime adaptation, the source manga provides more depth to her background. The story explores how she and Narumi became partners, revealing her fierce dedication and the origins of her switch from indoor to beach volleyball. Throughout the series, she and Narumi are shown to be consistently strong, ultimately defeating Haruka and Kanata in the finals of a major tournament. Despite the loss, Ayasa is impressed by the progress the protagonists have made, showing her respect for their growth.

On the court, Ayasa is a powerful and technically proficient player. Her most notable ability is her skill in reading opponents. However, her true strength is the synergy and unshakable trust she shares with Narumi. In key matches, the pair is shown to be capable of changing their style on the fly, making them difficult to read and counter. This ability to adapt seamlessly with her partner makes her half of a championship-level team.