Kaori Otsuki is a well-liked elementary school teacher with a big-sisterly disposition.

She moves to a new school to replace a teacher who has been hospitalized with stress.
On her first day teaching the 3^rd form 5^th grade class, she’s pelted with balls and called names by the students, but faces the abuse calmly. She finds out that Hana, a particularly violent female student, is being bullied by three male classmates.

But when Kaori moves to confront them, she faces resistance from the school principal and counselor, who refuse to acknowledge any bullying.