Ep 16. Reverse Decisions

After Yusuke's close victory over Chu, the spirit detective squad takes a brief break before being summoned to Genkai's temple for a new mission. At the temple, everyone gathers to learn about the next tournament that will determine the new ruler of the spirit world, which will commence soon. To their surprise, Koenma also reveals that the team's next mission will be to retrieve an item - the Shadow Sword - that is vital to the tournament.

It is said that whoever wields the sword can control their opponent's shadow during fights. The team expresses some confusion as to why Genkai didn't participate in the tournament herself. She explains that she participated in the tournament before, decades ago, and lost despite having the sword. Her opponent in that tournament was a demon named Suzaku, who later became one of the four spirit rulers of the spirit world.

Genkai shares that back then she used to go by the name "Dark Angel," and that in order to get the Shadow Sword, the team will have to win the underground tournament hosted by the Black Book Club. The members of the club include humans and demons who are feared and respected for their lethal abilities. The team is given one week to prepare for the tournament and Genkai reveals that she has a technique that will allow her to transform into her younger self, which she will use to enter the tournament and retrieve the sword.

Before the team can focus on the upcoming mission, Kuwabara requests Yusuke's help in saving Yukina, his lover. Yukina is the younger sister of Hiei, one of the four spirit rulers, and Kuwabara had promised to protect her. However, she has now been kidnapped by Tarukane, a major human trafficker who captures and sells demons. The team devises a plan to infiltrate Tarukane's castle and rescue Yukina. Yusuke, Kurama, and Hiei go inside while Kuwabara waits outside to provide backup and transportation.

Once they reach the castle, they split up to find Yukina. While searching, each member of the team faces their own challenges. Yusuke encounters new enemies and must use his powers and quick thinking to defeat them. Kurama uses his knowledge of medicinal herbs to create a diversion and Hiei uses his incredible speed and sword technique to slice through adversaries. Finally, they find Yukina and attempt to escort her out.

However, their escape is blocked by a powerful demon named Gourmet. Gourmet is a former acquaintance of Hiei, who has come for revenge. After a grueling battle, Gourmet is defeated and the team escorts Yukina to safety. With their rescue mission accomplished, they head back to Genkai's for some rest and to prepare for the underground tournament.

The team decides to keep their successful rescue of Yukina from Koenma to avoid any complications in their upcoming mission. At the underground tournament, Genkai easily defeats her opponents while Yusuke and his gang operate undercover to gather information about the Black Book Club. Yusuke comes face to face with his old enemy Toguro, who has joined the club. Yusuke believes that Toguro has entered the tournament to help retrieve the sword. Yusuke also unexpectedly meets with Kuwabara, who has come to watch the tournament, and informs him of their plan.

As the tournament goes on, it becomes increasingly clear that the Black Book Club operates with very few rules and that the lives of the participants are in constant danger. Eventually, Genkai is pitted against Kazemaru, a powerful opponent whose powers come from wind. The fight is intense and Genkai sacrifices herself for the team to win the sword.

The episode ends with the team mourning the loss of Genkai, but with the knowledge that they now have the Shadow Sword and can move on to the next mission. This mission leaves Yusuke and his friends, including the audience, with a sense of unease as the tournament was particularly brutal. The episode highlights the team's commitment to one another as they face difficult challenges and dangerous enemies, leaving them to wonder what will happen next.