|Episode Title||Characters Introduced|
|Seiryu, the Blue Dragon||Seiryuu|
At Reikai, Koenma and George comment happily on Kuwabara's great 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 Yuusuke that this is the secret of the Castle; only one door takes to where they want to go, while all others lead to deathtraps. Yuusuke asks Kuwabara to choose a door.
Using his reiki, Kuwabara detects the Beasts' ki behind the third door at left. Hiei is skeptical about Kuwabaraís 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. Yuusuke finds that hilarious, because Kuwabara fought against a giant Tiger beast, but is afraid of a rat.
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 reiki among the invaders, someone who can guide the group to the easiest and safest way. Seiryuu says that he will extinguish the all the Tantei, and commenting that Byakko and Genbu are weaklings.
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. Yuusuke 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 surrounding them. The giant Seiryuu appears in a burst of light. Yuusuke 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 hot acid pool.
But Seiryuu refuses his companion's plea, he tells Byakko that he is nothing but failure. He uses his powers to freeze Byakko up 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 any of them to see it.
Byakko's frozen and decapitated head still manages to speak asking Seiryuu as to why he did what he did. 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, the former opponent now a creature to help. Yuusuke is ready to fight, but Hiei stops him, telling Yuusuke to save his power against Suzaku, the last of the beasts.
Hiei steps forward and takes off his cloak, using it to respectfully cover Byakko's head. Seiryuu laughs at Hieiís sudden act of sentimentality, he also comments that Hiei should be a bit less soft that he shows.
Kurama says he never saw Hiei like this. According to Kurama, Hiei formerly acts like Seiryuu, but for some reason, he despises the act Seiryuu has done. Kurama thinks Hiei is re-evaluating his priorities, and that is causing his ki to grow to a higher level. And besides this, it seems that Hiei eagerly wants to finish off Seiryuu, and at the same time bringing a bit of justice to Byakko.
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, but Hiei only counters that Seiryuu will kneel before him.
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.
Yuusuke 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. Beast disdains that Hiei only has speed to his advantage, and also telling him that he will only tire running around. He keeps attacking Hiei with the freezing strikes, forcing the 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 suddenly hit and frozen; he lands on the floor, kneeling down to protect the frozen leg. Seiryuu mocks Hiei, telling him to surrender now. Hiei grits his teeth. But Seiryuu tells him that it is too late to repent, and the fate of Hiei will come down today, the fate of death.
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 are frozen.
Yuusuke is worried, but Hiei chuckles, saying that if Seiryuu believes that he can win by using ice power, then he is mistaken. And the ice on his limbs shatters like frail glass, freeing him from the freezing force.
Seiryuu is furious. Cursing and threatening, he tells Hiei that with his next strike itíll be all over, but a thick trail of blood runs down between his eyes.
Hiei smiles, at the same time telling the beast that there will be no more next strike. 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 truly see Hiei's attack.
Kurama says that he doesnít even know how many times Hiei slashes against Seiryuu. Kuwabara says that he wants to see the same attack again, well performed that is.
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. Yuusuke shocked, and comments that he only counted up to 15 slashes, and also says that he feels that the next time Hiei and him fight, there is no doubt that Hiei will win.
Hiei whispers that he isnít so sure that heíll win against Yuusuke. Kuwabara wonders and expects Hiei to at least give a conceited answer, but he didnít.
Kurama tells Yuusuke that Hiei is slowly changing, and that he seems to be having the same priorities as Yuusuke right now.
Enraged by this new defeat, Suzaku breaks the "crystal ball". A green little bird called Murugu flies in and tells Suzaku that she found Urameshi's weakness: she shows in an elliptical mirror the image of Yuusuke'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, and tells her that Yuusuke is nothing but a person who will pull her down. 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, something that is delicate being harmed. The four Tantei rush to find the last Beast, Suzaku, both to finish the fight and to save Ningenkai.