Young Japanese teacher Satoshi Yabe began working in the sixth grade of an elementary school, naively assuming that 12‑year‑old children would not bring any big surprises. That was the greatest mistake of his life, because the new homeroom teacher was expected by the Maruy sisters – the most dangerous triplets in Japan! The eldest, the cunning sadist Mitsuba, would outplan even Machiavelli. The middle one, the muscular athlete Futaba, appears outwardly unpretentious but has a… peculiarly developed imagination. And finally the youngest, the mysterious Hitoka – a living illustration of the saying "a quiet pond hides devils." These were the students awaiting in class 6‑B, a new sower of "reasonable, kind, eternal." From then on Yabe‑sensei"s life turned into a minefield where there was no room for error. In such conditions the young teacher will have to grow professionally, and we will learn a lot about life and relationships in the Maruy family. The main character still has to understand whether it is better when three cheerful sisters wish you well or the opposite!