Mayuko Shiraki is a teacher at Kaibara Municipal High School and serves as Tohru Honda’s homeroom instructor. She is generally good‑humored and can be playful with her students, once jokingly insisting they call her “Great Teacher Mayuko” after they used the familiar nickname “Mayu‑chan‑sensei.” At the same time, she is strict and no‑nonsense when needed: she stops Kyo Sohma from leaving class by putting a folder in his face and threatens to dye his orange hair black, and she breaks up a physical fight between Hatsuharu Sohma and Kyo by dumping a bucket of water over them. Her family runs a used bookstore, and she is their only daughter; her parents worry about her being unmarried.

Mayuko’s personal life is closely tied to the Sohma family. She became best friends with Kana Sohma during their university days, and through Kana she met Hatori Sohma, Shigure Sohma, and Ayame Sohma. Although she was attracted to Hatori, she genuinely wanted Kana and Hatori to be happy together. After Kana’s engagement to Hatori ended tragically when Hatori erased Kana’s memory, Mayuko was deeply hurt and at a loss. She later dated Shigure for about a month, but the relationship was distant and she realized she was only using it to alleviate her loneliness. She still harbors feelings for Hatori and resents Shigure’s continued interference in her life, even when that interference inadvertently brings her closer to Hatori. Over time, Mayuko moves from a state of self‑imposed emotional isolation toward a willingness to be vulnerable and pursue happiness for herself. By the end of the story, she and Hatori are shown as a couple, with Hatori inviting her on a vacation to Okinawa.

Mayuko is tall, and she is privately insecure about her height, though the author notes that Hatori is also tall, so they look well matched. In terms of appearance, she is described as having an androgynous beauty. As a teacher, she maintains professional rigor but also shows that she can have fun with her students. Her arc centers on reconciling her principled, straightforward nature with the courage to claim personal happiness after years of silent sacrifice.