In an ordinary middle school, the 1st-year B class is about to have a spring break. The ignorant students are making a lot of noise, not knowing that a storm that has lasted for months is coming towards them. The homeroom teacher, Yuko Moriguchi (Matsu Takako), completely ignores the chaos and quietly makes a final confession to the students. This single mother raised her lovely daughter (Aina Ashida) alone, but her daughter eventually drowned in the swimming pool. The police determined that it was an accident, but Moriguchi determined that her daughter died at the hands of two students in the class. She calmly accused the criminals A and B and announced that she would take revenge in her own way. After this, Moriguchi resigned as a teacher, and the students of the 1st-year B class also ushered in the spring break with anxiety. At the beginning of the new semester, a cruel storm hits this group of ignorant and fearless boys and girls... This film is adapted from Minato Kanae's original work, and became one of the top ten films in the 2010 Kinema Junpo; it won four major awards at the 34th Japan Academy Awards for Best Picture, Best Director, Best Screenplay and Best Editing.