Mayuko is the homeroom teacher for Tohru's class. She has a more masculine manner of speech, an open personality and is very popular. While Tohru and the other's don't know it yet, in the past, Mayuko and Shigure used to date for about one month. It's Mayuko who likened Shigure to small waves. She's a good friend of Hatori's former girlfriend Kana.

For girls she might be the ?? type.
That may be why Shigure liked her. Poor her... As it is, she's very popular with female students and has been put on the spot because they give her love letters and such. Lastly, she's tall and secretly is bothered by this.
But, Hatori is also tall so they make a tall couple which could be cool too. That's good.