Kanna Ando is a secondary character who becomes a classmate of protagonists Kyotaro Ichikawa and Anna Yamada during their third year of middle school, specifically in Class 3-1. She is known among the student body for her energetic and forward personality, though her face is almost always partially obscured. Kanna consistently wears a medical face mask that covers the lower half of her face, and on the rare occasions she is seen without it, her hair is typically positioned to hide her mouth. The specific reason for her mask-wearing is never explicitly stated within the story, though it is speculated to be due to health concerns such as illness or allergies. Her physical appearance includes medium-length hair that is a brownish-purple color, which she usually styles into twin-tails secured with small black ribbons, and she has brown eyes.

Kanna's most defining characteristic is her intense and enthusiastic interest in the romantic relationships of her peers, to the point of being described as having an obsession with celebrating other people’s couplings. She is highly proactive in this interest and has a particular desire to see her classmate Ichikawa develop an interest in someone. Her approach to celebrating romance is notably public and often intrusive. She works together with her friends to organize unsolicited flash mobs for unsuspecting couples, complete with congratulatory banners and confetti, without always considering their consent or desire for privacy. This causes significant complications for Ichikawa and Yamada, who are trying to keep their evolving relationship quiet and avoid public exposure.

Despite her intrusive actions, Kanna is not portrayed as malicious. Instead, she appears to have a genuine but limited awareness of social boundaries and the potential negative consequences of her behavior. Following a public rejection that resulted from a flash mob confession she helped facilitate, she displays a genuine lack of understanding as to why another character would be upset with her, indicating that her focus on celebrating romance may blind her to the personal discomfort she causes. In the classroom, her tendency to speculate about who likes whom and encourage public confessions puts Ichikawa on high alert, forcing him to be even more cautious about hiding his true feelings for Yamada. Outside of her social activities, Kanna is a member of the school’s cooking club, where she participates alongside her classmate Moeko Sekine.