The main character is an average student. But one day, a woman knight and two princesses suddenly transfer to his school and he is told to take care of them...

As a matter of fact, the princesses have a secret. There is a traditional custom in their country that the more beautiful breasts they have, the more they are admired. There is also a legend, "the country prospers by beautiful breats taken care of the soldier in the east." The princesses came to his town to look for the "soldier" and he is the one, according to them.

How can he make their breasts beautiful? But he, who loves breasts, is delighted to be chosen. His happy school life now begins...