Mochizuki Emiri

The student body president feared by teachers as well as students.
At first glance she seems lovely, but inside she's a cold-blooded sadist.
Using her authority, she reforms things as she see fits.
Emiri manipulates everyone and enjoys herself.
This is allowed because her family is one of the wealthiest in the country and are benefactor of the school.
As the daughter of a high-class family, she has no mundane knowledge and is ignorant about sex besides what's in the textbook.