This article contains details from the manga that are not covered in the anime. Proceed with caution.
Kaya was a cute young girl with brown eyes. She had short dark brown hair and a fringe swaying to the left side of her face. She wore a simple robe held by a long sash on which she tied in a ribbon and a scarf on her neck.
Kaya was a kind and considerate girl who took care of other people despite her state. Due to her illness, she secluded herself away from people to prevent spreading the disease and pushed away people who try to help her as she feared that she will infect them. Besides this gloomy attitude of hers, she can be childish and will refer to herself in third person if she wants to remind herself of her own name. With the time she spent with Zeno, she became a lively and friendly person who enjoyed her last moments of life to the fullest.
She took care of Zeno despite not knowing who he was and gave him a temporary home. Initially, she wanted him to leave after he recuperated because of her illness, but she let him nurse her while they spend the days together with glee. When Zeno proposes to her, she was left speechless until she cried out of joy. She was by her husband’s side till her last breath.
(To Zeno) 'Thank you for everything. Let's meet again, above the skies'