Mika Kujiin is a supporting character in the anime Kanamemo. She works as a newspaper deliverer for a rival distribution center to the one where the main character, Kana Nakamachi, lives and works. Despite her job, Mika is reluctant to admit that she delivers newspapers unless directly confronted about it. She transferred from a school called White Rose Academy, though the reasons for her transfer are not explored in depth.

Mika has a proud and somewhat prickly personality. She is quick to blame others for problems and frequently turns her own mistakes into inconveniences for those around her. This defensive attitude is a central part of her character, but it also masks a more caring and vulnerable side. She often uses a haughty, tsundere demeanor to keep people at a distance, yet she is not genuinely malicious. Her primary motivation appears to be maintaining a sense of pride and independence, especially in the competitive environment of newspaper delivery.

Her role in the story is that of a friendly rival to Kana. They first meet when Mika gets lost during her delivery route and literally runs into Kana. Mika forgives Kana by allowing her to escort her to the next stop, an act that reveals her underlying need for help even as she tries to appear self-sufficient. Over time, their rivalry softens into a genuine friendship. Mika attends summer classes with Kana and helps her practice smiling for a newspaper promotion, showing a willingness to assist despite her usual prickly attitude. She also joins in group activities such as visiting a public bathhouse and participating in a pool promotion, indicating a growing comfort with Kana and her coworkers at the Fuhshin Gazette.

In terms of development, Mika gradually opens up and becomes less confrontational. Her tsundere traits remain, but she learns to cooperate and even show kindness, particularly toward Kana. She does not have any supernatural or special abilities; her notable skills are limited to her bicycle delivery work and her ability to maintain a competitive edge against the rival newspaper office. Her physical appearance includes long pink hair often styled with braids and a hairband, and she is typically seen in shorts.

Key relationships include her ongoing rivalry-turned-friendship with Kana, as well as her interactions with the other members of the Fuhshin Gazette. She is not a main resident of that office but becomes a recurring presence in their social circle. Her motivations revolve around her job, her pride, and her gradual acceptance of friendship. Overall, Mika Kujiin serves as a foil to the more earnest and adaptable Kana, and her character arc highlights themes of opening up to others and overcoming a defensive nature.