Episode 176

Sesshomaru in the Underworld is the 9the episode of InuYasha: The Final Act.

Plot
Because he now lacks the super speed his jewel shards ganted him,, Koga decides to retire from the fight against Naraku, collecting his companions  and heading back home; the vengence for the members of the Wolf demon tribe Kagura slaughtered on Naraku's orders is now another duty of Inuyasha's group.

Meanwhile, Sesshomaru visits his mother to ask how he can make his Meido Zangetsuha stronger. The presence of Rin and Kohaku confuses her; Sesshomaru hated humans before, making her wonder if he's planning to eat them. Using a Meido stone left by Sesshomaru's father, she opens a Meido, allowing a Hell Hound to emerge; slaying it will stengthen the Meido Zangetsuha. However it quickly swallows Rin and Kohaku, taking them back through the portal. Sesshomaru gives chase, easily slaying the Hell Hound. However, while Kokaku is able to move freely, Rin is quite weak; Kohaku carries her on his back while they track through the darkness.

Watching this with Jaken, Sesshomaru's mother explains that the path they're on leads to the Underwold; Sesshomaru will never be able to return from there if he walks all the way down the path. She then wonders about Rin and her connection to Sesshomaru is. Jaken says Rin is very important to him. In return, she says Rin will not last long in the poisonous vapors of Hell.

Kohaku infroms Sesshomaru that Rin stopped breathing, something that shocks him in place. He orders Kohaku to place her down and attempts to revive her again with Tenseiga; however, he cannot see the paulbeares of the Underworld, something that fills him with despair. At that moment, the darkness of the Abyssal Void envelopes her and speeds off. In the World of the Living, Jaken then asks Sesshomaru's mother if she intends to let him die in the Underworld; she retorts she is not completely heartless, and will open a path back home.

Back in the Underworld, Sesshomaru is still giving chase to Rin just as the portal back to the World of the Living opens; his mother urges him to come back as Tenseiga has been strengthened. However, he completely ignores her and continues heading after Rin. Annoyed her son would ignore her, Sesshonaru's mother decides to leave him to his fate. Sesshomaru soon comes to a heap of bodies and an Underworld guardian, killing the latter. Holding Rin, Sesshomaru grieves to himself, saying gaining power is not worth her life. The corpes begin climbing towards Tenseiga, wanting salvation; Sesshomaru holds Tenseiga and sends out a pillar of light, appeasing their souls.

A Meido opens in the World of the Living, and Sesshomaru exits with Rin's body and Kohaku. Laying Rin down, Sesshomaru turns away, unable to bear looking at the one who died because of his greedy desire to strengthen Tenseiga. Sesshomaru's mother tells him that Tenseiga was limited to "one revival per person"; one can only bend the laws of life so much. Jaken begins crying, explaining that Sesshomaru is not one to do so, so he is doing so on his behalf. Realising Sesshomaru valued the human girl's life over power, his mother tells him she will only do this once. She places the Meido stone on Rin. Shockingly Rin opens her eyes. Sesshomaru touches her face to confirm her warmth. Sesshomaru's mother asks Jaken if her son is now happy; Jaken replies "extremely so", making her retort Sesshomaru is becoming more like his father.

Upon leaving, Sesshomaru's mother inquires as to how Kohaku could survive in the Underworld, but Rin couldn't; he explains about the shard in his neck, earning a warning that Tenseiga cannot save him if the shard is removed.