Ever since Yusuke has became so song since his training with Raizen.
Yukina ends up living with Kuwabara, not in that way, just as friends people.
The most surprising thing is what Kurama reveals; That the whole time the Spirit World had been brain washing D-class demons, or weaker ones to attack the human world so they could be thought of as bad, while Spirit World looked like the protectors. Koenma caught his dad in the scandal and overthrew him. In the end, he is the ruler of Spirit World. Still as a threat, Koenma kept his eyes on Yusuke, just in case something happened.
As three years went by, nothing out of the ordinary has happen, except one thing. There was a human extremist that knew about demons. He was a scientist that had developed a drug to enhance the human body. How will Yusuke know about this danger since he was dropped down as a Spirit detective? Will anyone stand up to this human who wants to kill all demons with his new warriors. Or will the he be the one to open the Demon World portal and cause hell, in hell?
Yusuke owns the Ramen store with his wife, Kikyo. Hiei is no where to be found, maybe he is in the demon world off somewhere. Kurama is with his human family, but he is searching for his old teammates as he found out what the human has started. Kuwabara is at his house working for the police department protecting his good friend Yukina from any harm.