Shiraki Mayuko

Shiraki Mayuko also referred to as 'Mayu-sensei', is Tohru,Kyo,Yuki,Saki and Arisa's homeroom teacher. The subject she teaches was never specified, but in an author's note, Natsuki Takaya stated it is probably Literature.

Her parents, who worry about Shiraki being unmarried, run a bookstore where she sometimes helps out. Takaya said in an author's note that Shiraki is "possibly sad" that she is a woman and "secretly insecure of how tall she is", but since Hatori is tall too, they "might look pretty good together as a tall couple".

Background
Not much of her past is reveal.

Appearance
In school, she keeps her hair tied but in some instances, she brings her hair down. It's possible her hair is either brown or blonde. Near the end of the series, she cuts all of her hair off.

Personality
Shiraki is depicted as generally good-humored but sometimes aggressive.

Fruits Basket (Manga)
Originally Mayu-sensei seemed to be nothing more than the main casts homeroom teacher although it is later revealed (and hinted in book 7) that she is/was old friends with Kana Sohma, Hatori's old love and Shigure Sohma's ex-girlfriend, although the two parted on rather bad terms seeing as how they were only together because neither wanted to be alone, only the faux relationship made her feel more isolated.

Mayuko was stunned and heartbroken during Kana's mental breakdown unsure how to comfort her friend when she was not allowed to know the full details. She was later shown meeting up with Hatori then inviting him out to a drink, she seems on at least good enough terms with Ayame Sohma seeing as how she sent him some copies of Kana's wedding photo's.

Sohma Kana
Shiraki's best friend is Kana,Hatori's former fiancee. Ever since they were in college, they've been together. When Kana introduced Hatori to Mayuko, Mayuko fell in love with him, but kept it secret from Kana since she knew from their actions that they have a relationship. It's noted that Mayuko still keeps in touch with Kana after her break up with Hatori and marriage to her new husband.

Sohma Ayame
She seems to get along with Ayame very well.

Sohma Shigure
She was dating Shigure for about 1 month before they broke up, because Shigure was only dating her out of sympathy. Shigure keeps in touch with Mayuko by visiting her parents' bookshop. At one point, he playfully asks her to start dating him again, only to be rejected. He actually sets Mayuko up with Hatori as a way of making it up to her.

Sohma Hatori
She had a crush on him, but refrained from acting upon it because of Kana. However, throughout the series, she and Hatori share mutual attraction, and in the end start dating.

Trivia

 * She doen't appear in the anime.
 * In the final chapter, Shiraki and Hatori are shown as a couple, with Hatori inviting her on an Okinawa vacation.