At Reikai, Koenma and George comment happily on Kuwabara's victory. The oni found a book about beasts in the library and Koenma flips the pages eagerly, looking for information on the two remaining Beasts. However, he soon realizes that he's reading a recipe book. Annoyed, Koenma summons two other ogres that take George away to be punished.

In the castle, the four Tantei reach an empty chamber with several doors. Kurama warns Yusuke that this is the secret of the Labyrinth Castle; only one door takes to where they want to go, while all others lead to deathtraps. Yusuke asks Kuwabara to choose a door.

Using his reikan, Kuwabara detects the Beasts' ki behind the third door at left. Hiei is skeptical about the human boy's skills, but Kuwabara walks decidedly to the door he chose and opens it, announcing that he feels a powerful source of evil energy coming from that path.

Kuwabara screams in terror. There was a mouse behind the door. Yusuke finds that hilarious: "He fights Beasts and is afraid of mice?!"

The two remaining Beasts, Suzaku and Seiryuu, watch the approach of the Tantei through a "crystal ball". Suzaku recognizes the presence of someone with strong reikan among the invaders, someone who can guide the group to the easiest and safest way. "Don't worry, Suzaku-sama," says Seiryuu. "Genbu and Byakko were inferiors. I promise to get rid of all of them, and together we will strike the Ningenkai."

Botan reports to Koenma from Ningenkai, saying that the zombies' attacks are still restricted to a small area of the city, but the demonic insects are biting more and more humans. Yusuke has to destroy the Flute fast or the entire Tokyo might be taken.

The four Tantei find Seiryuu's chambers behind a huge gate flanked by dragon gargoyles. They step inside and are impressed by the youki level surrounding them. The giant Seiryuu appears in a burst of light. Yusuke snorts about both his height and arrogance.

But a dragging sound interrupts the conflict. Burned and battered, Byakko comes in and asks Seiryuu for a bit of ki, promising to return it as soon as he heals. Kuwabara and the other boys are overwhelmed at Byakko's courage and persistence, and shocked to see him still alive after having fallen in the acid pool.

But Seiryuu refuses his companion's plea: "I don't need you anymore. Now you're nothing but a nuisance." He uses his powers to freeze Byakko and kicks him, shattering his body. Then he boasts to the four boys, telling them that he used a hundred freezing punches in a few seconds, too fast for them to see it.

Byakko's frozen and decapitated head still manages to speak, "Seiryuu, why?" Seiryuu says he doesn't need weaklings at his side, and spits on Byakko's face. Byakko dies, a teardrop freezing in the corner of his eye.

The four Tantei are furious at this coward act of betrayal. Not only they wish to defeat Seiryuu, but also avenge Byakko's death. Yusuke is ready to fight, but Hiei stops him: "Save this anger to fight Suzaku, the last of them."

Hiei steps forward and takes off his cloak, using it to respectfully cover Byakko's head. Seiryuu laughs, "I don't believe it. Even you acting on sentimentality now, Hiei? You and I belong to the same world, the evil path."

Kurama says he never saw Hiei like this. "In the past Hiei acted just as Seiryuu does. Now he looks at Seiryuu and doesn't like what he sees." Kurama thinks Hiei is re-evaluating his priorities, and that that is causing his ki to grow to a higher level.

Both fighters ignite their auras. Seiryuu's emanates a cold fog that spreads throughout the room. Hiei's shines in pale blue shades around him. Seiryuu suggests that Hiei should join the Beasts by keeling down and acknowledging their superiority. "You're the one who's going to kneel," Hiei retorts.

Seiryuu attacks with a wave of freezing smoke. Hiei uses the katana to form a shield to protect himself and his companions; the smoke hits the wall behind them and destroys part of the concrete.

Yusuke sees Seiryuu preparing the same attack he used to kill Byakko and warns Hiei, who jumps over Seiryuu's head, landing on the other side of the room. "Your only skill is your speed," the Beast disdains. "How long can you endure this?" He keeps attacking Hiei with the freezing strike, forcing the short demon to run/jump/blur out of the way. Every time he misses, but the walls, floor and ceiling are getting completely covered with ice. Kuwabara is shivering with the growing cold.

Hiei's left leg is hit and frozen; he lands on the floor, kneeling down to protect the leg. "So you decided to capitulate?" Seiryuu mocks. Hiei grits his teeth. "But now it's too late," the Beast says. "It's useless to plead for mercy, your destiny has been sealed. Die!" He attacks again.

Hiei stabs the floor with the katana, using the sword as a lever to propel himself forward, then quickly brings it to an attack stance as he flies towards Seiryuu. The freezing wave and the blade meet in a white blur, and Hiei lands near the Tantei, his left arm and both legs frozen.

Yusuke is worried, but Hiei chuckles. "If you think you can vanquish me with this kind of power, you're very mistaken," Hiei tells Seiryuu. The ice on his limbs shatters like frail glass, freeing him.

Seiryuu is furious. "I'll kill you with my next strike!" But a thick trail of blood runs down between his eyes.

"There won't be a next strike," says Hiei. Slashes pop up throughout Seiryuu's entire body and the Beast vanishes in an explosion of white light. The other three Tantei are impressed; none of them managed to see Hiei's attack.

"I have no idea of how many times he cut him," Kurama admitted.

"I wanna see that again!" Kuwabara exclaims.

The walls of the room unfreeze and Hiei ceremoniously sheathes his katana. Asked by Kurama, Hiei tells them that he slashed Seiryuu's body sixteen times. "Sixteen... I only got to count fifteen," Yusuke half-moaned, half-bragged. "That was incredible, Hiei. If I had to fight you again, I'm sure you'd defeat me."

"I'm not so sure," Hiei whispers, stepping away. Kuwabara is puzzled; he had expected Hiei to answer the challenge by saying "of course".

"Since we came here, he changed a lot," Kurama tells Yusuke. "Little by little, he's starting to follow your footsteps." Yusuke smiles as he watches Hiei redressing his cloak - Byakko's head vanishes.

Enraged by this new defeat, Suzaku breaks the "crystal ball". A green little bird called Muruge flies in and tells Suzaku that she found Urameshi's weakness: she shows in an elliptical mirror the image of Yusuke's girlfriend, Keiko Yukimura. Pleased with the information, Suzaku plays the Flute, summoning the zombies to attack Keiko.

In Ningenkai, a despaired Botan calls Koenma and tells him that the zombies started to attack in packs and she lost control of the situation. He tells her to come back to Reikai before she gets killed, but the zombies surround her. Botan closes her eyes and brandishes the baseball bat, but no attack comes. The zombies heard a change in tune from the Flute and walk towards the Sarayashiki School. Botan follows them.

Inside the school, Iwamoto-sensei tells Keiko to go home and study for the test tomorrow. He also warns her to keep her distance from Urameshi. When the teacher turns to leave, she sticks her tongue at him; but since she has no powers, she can't see the demonic insect crawling into Iwamoto's ear.

Moments later, Iwamoto returns, already turned into a zombie. He tries to punch Keiko and she runs away in panic. She reaches the front door of the school, but a group of zombies is waiting for her. She tries to escape, but is soon surrounded.

In the castle, Kuwabara senses that something terrible is happening back in Ningenkai. The four Tantei rush to find the last Beast, Suzaku.