Natalia "Mimi" Medin is Tatsuki's school Representative and Captain of their girl's soccer team. Her teammates and the overwhelming amount of fan-girls and boys address her as "Mimi" although no reason for her to have such a nickname is given.
Beautiful, athletic, and smart, Tatsuki is head-over-heels in love with her, believing that she could be the very Mimi he had grown up with. Tatsuki harbors this passive obsession for his four years of watching her. After Misaki's arrival which is late into the spring of his senior year, Tatsuki attempts several times to impress Natalia, with the end goal of asking her to Prom in mind.
Misaki shows only contempt for Natalia, and often gets in the way when Natalia voluntarily spends time with Tatsuki. Yukihiro is not a fan of Natalia's either, but does whatever he can for his lovelorn friend.