In the era of Edo Japan, a warrior clan known as the Manyuu possesses a unique magical skill to alter a woman's breast size with a sword strike. In Manyuu Hikenchou, breast size symbolizes power and influence. When the clan's heir, Chifusa, rebels against their breast-obsessed society by fleeing and stealing their sacred scroll, she sparks chaos within the clan. With the loyal warrior Kaede by her side, Chifusa faces danger as a fugitive from her own people. As they aim to dismantle the oppressive norms, Chifusa uncovers an extraordinary power within herself that could revolutionize the realm for the better.