Yoichi Karasuma has lived his entire life in the mountains, training in the Soaring Wind, Divine Wind swordsmanship style. Guided by his father, he masters the technique at the age of 17. With nothing left to learn, Yoichi is sent to a new dojo in the city to continue his training and gain an understanding of modern society. Unfortunately, Yoichi has no idea how to act or speak to anyone in the present day and behaves like a samurai, complete with odd speech and traditional clothing. As he goes to live with the Ikaruga sisters at the dojo, Yoichi, clueless on how to interact with others, is constantly hurtled into hilarious misunderstandings. Asu no Yoichi! follows Yoichi as he stumbles through his new life and tries to learn how to live in the modern world with his new family.