It is currently the Taiheimeji Era, an era ruled by the Tokugawa Shogunate. A group of warriors who support the government known as the Manyuu Clan exist. In this era, large breasts mean everything. If you have them, you are guaranteed wealth and popularity. If you lack them, you are barely considered "human". Members of the Manyuu Clan help to raise the future "big breasts". Chifusa, the successor of the clan, steals a secret scroll that is said to have various techniques detailing how to grow big and beautiful breasts, hoping to put an end to this cruel system the Manyuu have created.