The 26-episode storyline follows the young (72 years old) "doushi" (Apprentice to a Sennin) Taikoubou as he is told to go from the Sennin (Immortal) world to Earth (and specifically Yin China) to hunt down 365 renegade evil spirits in order to bring down the fall of Queen Dakki, a Fox spirit who has enslaved the Emperor.

Taikoubou recruits Nataku, a human/weapon hybrid, and Raishinshi, a would-be vigilante, in his quest to hunt down Dakki. He also rides a talking hippopotamus named Suppushan, who remains the most popular character of the series.

Ki Shou, the Lord of the West, is a man who is unwittingly destined to found the Shou dynasty. Imprisoned for trying to stop Dakki's evil, he suffers a grevous wrong when his son is murdered and served to him as a meal. Escaping from his captors, he returns with an army to overthrow the Yin with the help of Taikoubou.

In the midst of this historical drama, the Immortal High Council is plotting some form of magical spell that requires the capturing of many souls that they deliberately lie about the purpose of the Houshin Project to young Taikoubou.