Episode 18

Naraku and Sesshomaru Join Forces is the eighteenth episode of the InuYasha anime. It first aired in Japan on March 5, 2001.

Synopsis

 * 1) Naraku gives Sesshōmaru a human arm, with a shard of the Shikon no Tama embedded within it, so that he can wield the Tessaiga; he also gives him the hive of the Saimyōshō, to combat Miroku's Kazaana.
 * 2) Sesshōmaru steals the Tessaiga, and uses it against Inuyasha; Sesshōmaru utilizes Tessaiga's true power, the ability to destroy 100 yōkai with a single stroke.

Summary
The episode begins with a group of bandits coming across Sesshōmaru. He slays them using his newly acquired left arm which formerly belonged to a blue demon, but the arm is rendered useless shortly after. Jaken recounts the tale of how Inuyasha used the Tessaiga to sever his arm in their last encounter.

A man wearing a baboon pelt appears before Sesshōmaru having overhead his conversation with Jaken and expresses how he also despises Inuyasha. He offers him a human arm that has a shard of the Shikon Jewel embedded in it and informs Sesshōmaru that with this arm he will be able to wield the Tessaiga. In exchange, Sesshōmaru will exact revenge on Inuyasha for him. Sesshōmaru tells the man that he wants to know the name of the one he makes a pact with. The man tells him to call him Naraku.

Meanwhile Inuyasha, Kagome and Shippō are eating at a tavern while Miroku is performing an exorcism. Inuyasha confronts Miroku about his powers saying that whenever they are looking for a place to stay, Miroku mysteriously detects an ominous cloud over the finest tavern in the area. Miroku admits that there never was a black cloud. Although Shippō is surprised, Kagome thinks to herself that she was beginning to suspect that, too. Miroku offers Inuyasha a plate of dumplings as a peace offering which Shippō takes. Kagome tells everyone to settle down as the ground beings to shake.

Inuyasha says that whatever is coming, it is big. Kagome senses that a jewel shard is fast approaching. Inuyasha comments on how the jewels don’t usually come to them. Miroku and Inuyasha race after the jewel shard. The gigantic demon ogre appears with Sesshōmaru and Jaken riding on its shoulder. Sesshōmaru says that he is there for the Tessaiga. Miroku asks if Inuyasha and Sesshōmaru know one another to which Kagome replies that they are brothers. Kagome thinks to herself that Sesshōmaru couldn’t wield Tessaiga last time and wonders what could have changed.

Inuyasha attempts to attack Sesshōmaru with Tessaiga. He avoids the attacks easily and comments on how Inuyasha has yet to release the full power of Tessaiga. On the next strike, Sesshōmaru grabs Inuyasha’s wrist. As the poison from Sesshōmaru’s nails burns Inuyasha’s flesh, Sesshōmaru asks which will be the first to drop, Inuyasha’s wrist or the sword. Inuyasha comments that it won’t be the sword as he briefly overpowers him.

However, Sesshōmaru manages to knock the Tessaiga out of Inuyasha’s hands. To Inuyasha and Kagome’s surprise, Sesshōmaru is able to grasp the sword with his left hand. Jaken summons all the demons from the mountain, and Sesshōmaru demonstrates the true ability of Tessaiga, the ability to slaughter 100 demons with a single stroke.

When Kagome starts to run toward Inuyasha, Miroku tells her to wait. He steps in front of Inuyasha and says that he must put an end to “this foolish sibling rivalry.” As Inuyasha and Miroku argue, Jaken wonders if this is the monk that Naraku claimed could be more troublesome than Inuyasha. Unconvinced that he is a worthy opponent, Jaken asks Sesshōmaru if he can finish the monk off. When he goes to attack, Miroku unleashes the wind tunnel. Kagome exclaims that Miroku is the best. Then she turns to Inuyasha as an afterthought and says that he was good, too. Inuyasha sarcastically says that he could tell that was from the heart.

Sesshōmaru recalls how Naruku gave him the nest of the Saimyōshō to plug up the hole in the monk’s right hand. He releases these poisonous wasps from hell, and they fly toward Miroku’s hand. Miroku closes up his hand and tells Inuyasha that he will have to take over. Inuyasha uses Sankon Tessō to attack the wasps. Miroku tells Kagome that the insects have poisoned him with their venom. She tells him not to move as she runs off to get an antidote. As Inuyasha grabs Miroku to escape, Inuyasha says the Miroku is going to owe him big time. Then it occurs to him that Miroku could be in serious trouble.

As Sesshōmaru approaches, Inuyasha realizes that they are trapped and can be done in with a single strike of the Tessaiga. Sesshōmaru tells them that this is the end as he sends another attack towards them. They manage to survive by hiding behind the fallen gigantic demon ogre. Sesshōmaru tells them to run and hide while they can because it is the only choice left for them. On the other hand, he says that Inuyasha would at least die with honor if he stands up and faces his death.

Unimpressed, Inuyasha replies that if Sesshōmaru intends to kill someone, he better do it right the first time because they tend to have a nasty way of coming back to make you regret it. Inuyasha goes to attack Sesshōmaru. When Sesshōmaru goes to strike back, Inuyasha blocks the attack with the sheath of Tessaiga.

Jaken emerges from the rubble contemplating that Sesshōmaru’s disregard for ally or foe during battle may be more worrisome than his actual power. To Jaken’s surprise, Miroku grabs him by the head and asks if he can explain how they knew to use the insects when they have never met before. Shippō tells Miroku to watch out as Jaken attacks them with fire from the Staff of Two Heads. Despite Shippō’s best efforts, Jaken counters his attacks. Miroku tells him to save himself to which Shippō responds that he is staying.

After Sesshōmaru knocks the sheath out of Inuyasha’s hands, he says that in one strike it will be over. Before he can unleash his attack, an arrow strikes Tessaiga and reverses its transformation. It is Kagome standing poised to shoot another arrow. Kagome commands Sesshōmaru to drop the sword otherwise the next arrow will strike his heart. Inuyasha calls out to her, but she tells him to stay back. Miroku thinks to himself that it must be true that Kagome is the reincarnation of the priestess.