A boy trained by his father in the way of the "Ukiha Kamikaze" swordplay, Yoichi, has lived in the mountains, far from civilzation for all seventeen years of his life. His father finds nothing more to teach him, and sends him to the city to lodge at the Ikaruga dojo to further his mental and physical capabilities. Four sisters live in the dojo and Yoichi begins a new more severe "training" regimen.

The first nine volumes of Asu no Yoichi! were published in English as Samurai Harem: Asu no Yoichi by Tokyopop from June 2, 2009, to August 9, 2011. The manga was also licensed in English by JManga but was never released. The series was published in French by Kaze; in Taiwan by Sharp Point Press; and in Italian by RW Edizioni under its Goen imprint from March 13, 2011, to January 19, 2013.