Ayano's mother, Hiyori's older sister, and Kenjirou's wife.

Ayaka had a cheerful and generous personality and cared for every member of her family equally; however, she was also unstoppable when angered, and that was part of what kept the family together. She was interested in the "Legend of Medusa" of the hometown from her childhood.

With the ambition to become a professional archaeologist she went to university to take a course, where she met Kenjirou, who was in the same class as her. They fell in love, married, and as time went by had a child named Ayano. At some point she heard of three kids with special abilities who had come to the orphanage. Her and Kenjirou eventually adopted Kido, Kano and Seto and she tried her best to help her husband in understanding their powers. She died as her and her husband got caught in a landslide they were researching.
In the true ending, once Mary opens up the Heat Haze to the world, she is reunited with Kenjirou, who decides to stay in the Heat Haze with her.
(Source: Kagerou Project Wikia)