Matsuri Mizusawa is a 14-year-old girl who is the yandere for Yuzu Aihara in the yuri Citrus.
When Matsuri was a young girl, she was often neglected by her parents. Eventually, Matsuri bonds with Yuzu because of their loneliness, and they began to act like sisters. From there, Yuzu would babysit Matsuri before ultimately moving a way when her mother remarried. Since then, Matsuri had become possessive of her. During her time by herself, she also had the tendency of conning older men out of their money by posing as a camgirl. However, she rectifies this by stating that the videos are actually of random women during her browsing sessions.
Matsuri makes her first appearance in chapter 8 of the anime entitled "Out of love" consoling a heartbroken girl who had recently broken up with her boyfriend. However, it is heavily implied that Matsuri was the one responsible for breaking the two up as she insults both of them under her breath. Matsuri later enters into the conservative all girls school unnannounced, and she meets Mei. Realizing that Mei was Yuzu's stepsister by law, Matsuri goes about trying to sabotage the relationship between the two girls. One instance of this is hiring two boys to take a picture of Mei hitting her, though the results don't end up in her favor.
To this end, Matsuri kisses Yuzu to exert her dominance over Yuzu, and she tried to blackmail Mei into going on a date with one of her "internet friends" fully hoping that Mei would get raped by the assailant. As part of the plan, Mei insists for Yuzu to take Matsuri out on a date. Yuzu obliges, and meets up with Matsuri. Things seemingly go according to plan at first, until Yuzu began mentioning Mei by name. Enraged, Matsuri goes on a heated rant about how Mei was actually a "whore" and only using Yuzu. Yuzu silences her by heating her forehead against her own and calls out Matsuri for using people as objects to be manipulated, and attempts to force Matsuri into apologizing. Later on, she admits to Mei that she had failed at gettging Yuzu back, as well as realizing that she and Mei weren't as different as she thought they were.