Kajika is a fifteen-year-old girl who works as a steam blacksmith in Aragane Station. She has brown hair and brown eyes and typically wears the standard uniform of a steam smith.

Kajika is defined by her kind, gentle, and caring nature. She has a motherly and homely demeanor, often taking on domestic tasks such as cooking and looking after young children. She is known to be friendly and gets along well with her colleagues. However, beneath her sweet exterior lies a person with a strong will and a firm sense of principle. She is not afraid to speak her mind, even to those of a higher social standing, once slapping a samurai's hand and scolding him for trying to eat with dirty hands because the body is a gift from one's mother.

Kajika is motivated by a desire to support and protect those around her. At the start of the story, she expresses a wish to be as brave as her friend Ikoma, whom she admires for his courage to stand up to the bushi samurai. Her most heartfelt aspiration, revealed during a Tanabata festival, is to become a teacher, reflecting her fondness for children and education. Her motivations often translate into acts of quiet compassion, such as secretly giving an extra portion of food to a pregnant woman or caring for the children who have lost their homes.

Within the story, Kajika begins as a supporting character in the background of the maintenance shop, unharmed when her station falls to the Kabane because she was in the shop. As the survivors flee on the fortified train Koutetsujou, her role becomes more prominent. She volunteers for duties involving cooking and childcare, becoming a stabilizing domestic presence among the chaos. Her loyalty is significant; when Ikoma and Mumei are revealed as Kabaneri and confined to the last car, Kajika is confined with them for her association with Ikoma. In a key moment, she overcomes her fear to voluntarily offer her own blood to sustain the Kabaneri, demonstrating her deep commitment.

Kajika shares vital relationships with the main cast. She is a close friend and workplace ally to the protagonist Ikoma and his friend Takumi, supporting their efforts to fight the Kabane. Her most significant bond is with Mumei, the young Kabaneri girl. Kajika is the first person Mumei asks for blood, and she becomes Mumei's primary source of maternal care and friendship. She is one of the few people Mumei does not treat harshly. Kajika looks after Mumei, bathes her, buys her a flower ornament, and gives her a lap pillow, actions that provide the emotionally wounded Mumei with a sense of home and affection. This relationship allows Kajika to bridge the gap between Mumei and the rest of the human survivors.

Kajika shows notable development in her assertiveness. While initially portrayed as somewhat timid and admiring of bravery, she grows into a more decisive and outspoken individual. This is most starkly illustrated when Takumi dies; in a powerful moment of grief, Kajika abandons her usual gentle demeanor to curse the enemy while holding his body, shocking those around her. Despite this moment of rage, she survives the journey and continues to care for others, ultimately using her skills to help create a shelter for returning heroes.

Regarding notable abilities, Kajika is not a fighter. Her skills lie entirely in domestic and practical craftsmanship. As a steam blacksmith, she has technical knowledge of the trains and their machinery, working alongside Ikoma and Takumi. Her primary contributions are her skill in housework, including cooking and cleaning, her talent for childcare, and her ability to negotiate for goods, as she is shown to be very skilled at bargaining for lower prices when shopping.