Yusuke returns from training with Genkai to discover that his home city has been invaded by Makai insects inhabiting humans controlled by the Makai Whistle used by the four Saint Beasts. Yusuke and Kuwabara enter a hidden portal which takes them to the location of the Saint Beasts' castle. Kurama and Hiei, with the offer of pardons from their past crimes, have been sent to help Yusuke and Kuwabara with this new mission. Once inside, the four are faced with holding up a collapsed ceiling, trying not to betray one another in order to escape.