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. This turned out to be the greatest mistake of his life, because the newly appointed homeroom teacher was awaited by the Maruy sisters – the most dangerous triplets in Japan! The eldest, a cunning sadist named Mitsuba, with her plans would give even Machiavelli a run for his money. The middle one, a muscular athlete named Futaba – a girl who appears unpretentious on the outside but has a specifically developed imagination. And finally, the youngest, mysterious Hitoka – a living illustration of the saying "fierce devils lurk in calm waters." These were the students who awaited in class 6‑B a new sower of "reasonable, kind, eternal" wisdom. From then on Yabe‑sensei"s life turned into a minefield where there is no room for error. Under such conditions the young teacher will have to grow professionally, and we learn a lot about life and relationships in the Maruy family. And the main character still has to understand whether it is better when three cheerful sisters wish you well or otherwise?