Six months has passed and Yusuke has finally returned after having an intense training with Genkai. Keiko meets him on his return and treats him to an ice cream for their reunion. Yusuke, now fully relaxed, talks to Kuwabara and discusses their previous encounters (they're now best of friends!) Just then Keiko interrupts their conversation and Yusuke quickly makes an excuse by treating her to a movie...

As they were about to enter the movie house Yusuke senses something bad, and quickly makes up another excuse for Keiko (the forgot something and be back in a moment excuse), and together with Kuwabara, they leave Keiko behind. As the two walk off suddenly a group of punks attack them, but Yusuke finishes them off by unleashing his newly learned technique from Genkai, the Spirit Shotgun! this display of power even shocks Kuwabara off.. Then another punk tries to land a sneak attack on the two, but somebody turns in and smacks the punk out.. and it turns out to be Botan (yet again)... Botan then explains Yusuke's next mission...

Koenma receives a letter from the Shiseijuu (Sacred Demons) demanding the spirit world to allow them to stay in the human world before worse comes to worst. Then Botan explains that the punks that attacked them were possessed by insects that manipulate their mind into doing evil deeds. She tells Yusuke that this insects are controlled by a flute which is being used by the leader of the Sacred Demons, Suzaku. So the only way to stop this mess is to defeat the demons, since the spirit world will not grant their request of being able to stay in the human world. This serious talk suddenly comes to an end when Botan realizes Kuwabara was listening to them.. now Kuwabara learns about this whole thing, the demons, detectives and the rest, and because they are now best of friends, Kuwabara decides to help. Botan leads them to a secret tunnel that connects the human world to the sacred demons' castle. Without any hesitation Kuwabara jumps down, forcing Yusuke to follow.. but before Yusuke goes Botan gives him a communicator that will enable them to communicate between both worlds.. just then Yusuke remembers something really horrible.. he left Keiko ALONE in the movie house! as we see a very pissed Keiko ^_^ Yusuke jumps in the tunnel as fast as he could leaving Botan to explain things with his girlfriend (yet again)

Kuwabara and Yusuke arrive in the demons' castle only to be greeted by hundreds of zombies. Outnumbered by this monsters both Yusuke and Kuwabara are knocked down, but just then a strange light blinds the zombies off. We then see two familiar faces, Kurama and Hiei, and they are out to help Yusuke by orders of Koenma in this quest. They quickly get along with each other, as Yusuke introduces Kuwabara to the two. Hiei challenges Yusuke to another showdown once this thing is over, but then Kuwabara breaks in, and seeing how short (literally) Hiei is he starts to taunt Hiei... and a little misunderstanding arises (here starts their long-running hatred with each other).. as Yusuke breaks the one-sided brawl (with Hiei using his speed to evade Kuwabara's attacks).

The four warriors now enter the demons' castle only to be greeted by a flying eye monster. The monster pulls a lever and suddenly the ceiling falls off, leaving the four trapped beneath. Now the four are in one hell of a situation they desperately need to break out...