Eternal Love, The Naginata of Kenkon is the one hundred fortieth episode of the InuYasha anime.
- Hoshiyomi flashes back to his time with Tsukiyomi and remembers her supposed betrayal; Kagome is taken over by Tsukiyomi's spirit and explains what really happened all those years before: Hoshiyomi had been possessed by the Naginata of Kenkon, and she sealed him away to save him, with the intention of freeing him after she dealt with the naginata, though she died before she could.
- Despite reconnecting with Tsukiyomi, Hoshiyomi still maintains that he must kill all humans; he is finally killed by Inuyasha's Bakuryūha and his soul purified by Kagome's sacred arrow.
With the tear in the sky pulling in everything in the area, Hoshiyomi hovers in the sky holding an unconscious Kagome. One after another, Inuyasha, Sango and Miroku attack Hoshiyomi, all without success while Hoshiyomi gloats about the invincibility of his new weapon, the Naginata of Kenkon.
Hoshiyomi then asks if he (the question either being directed to Akitoki or Inuyasha) wanted Kagome back so much and if he loved her that much. Inuyasha appears as if he was going to answer, but Akitoki answers first and makes an impassioned plea for Kagome's life, confessing his love for her and saying he would gladly give his life in exchange for hers. Akitoki then makes a speech about how love never dies no matter how much time passes and that despite humans being weak, he says that is what makes humans special: weakness. It is weakness that makes humans able to understand the pain of another and to show kindness and compassion to each other. And that is why he feels that their feelings of love last forever.
She reminds him of their past, hunting demons together. Hoshiyomi confesses that he had the Naginata of Kenkon created in order that Tsukiyumi would not have to fight demons anymore. But Tsukiyumi saw the danger of the Naginata of Kenkon and that it was slowly possessing him, and sealed Hoshiyomi away until she could purify the weapon. She was able to separate the blade into two swords, the Ken blade and the Kon blade, but did not have the strength left to release her beloved Hoshiyomi before she died.
Hoshiyomi questions himself for a moment, but then rejects his former love refusing to believe her. He retrieves the Naginata to strike her image from the sky, and Kagome is released from the spell and falls to the ground. Inuyasha quickly catches her and sees that she is unconscious, but unharmed. Kagome, moments after this, awakens. Hoshiyomi then goes on to say how he has no regrets and still plans to rid the world of humans. Kagome then denounces Hoshiyomi saying his beloved died all for his sake and how he could ignore such a sacrifice, surprising Inuyasha at Kagome's outspoken words. Tessaiga pulses, signaling it has awaken, as Kagome goes on to say how Tsukiyumi may have been human but was not at all weak and had a much stronger heart than Hoshiyumi ever did. She then bluntly says Hoshiyomi betrayed himself and become bewitched with the blades power because his own heart was weak. This sends Hoshiyomi into anger and he goes to strike and kill her, but Inuyasha steps forward to protect Kagome from the attack, demanding Hoshiyomi as he blocks the attack, "Don't dare lay a hand on her. Stay away from her. I'll protect Kagome."
During Inuyasha and Hoshiyomi's battle, Kagome tries to fire an arrow at Hoshiyomi, but finds herself without the spiritual power she needs. InuYasha continues to battle, but is tossed aside. Akitoki, with a declaration of love, tries to stop Hoshiyomi from hurting Kagome when he attempts to strike and kill her once again by throwing himself onto him. Due to this, he yells out that he is in love with her and Hoshiyomi throws him and Kagome aside. With a prayer to Tsukiyumi for help, Kagome then gets up and fires another sacred arrow at Hoshiyomi again with Tsukiyumi's help, who manages to return Kagome's spiritual power.
Hoshiyomi is killed by Inuyasha's backlash wave and his soul is purified by Kagome's sacred arrow, admitting that things were better this way. Everything then calm, Shippō and Myōga make a comment to Inuyasha and Kagome that they were in "perfect sync" battling together. Akitoki, nearby, watches with a sad expression on his face realizing that his love will always go unrequited towards Kagome, possibly seeing her love for Inuyasha.
In the ending of the episode, at Hoshiyomi's or Tsukiyumi's grave, Inuyasha makes a comment saying Hoshiyomi was exactly the way he used to be that there had been a time when he had been completely possessed by his own demonic power and he couldn't even control himself. He then adds on it was still "exactly the same." Miroku then says that its a good thing he has Kagome since she had "embraced him with kindness" and saved him. Shippō then adds on how the first nice thing she did was tell him to "sit." However, this kills the moment with Inuyasha then getting into an argument about how Kagome wasn't "kind" at all towards him and Kagome arguing back with him. Akitoki, who is watching nearby hidden in the trees, silently asks her to take care of herself as he then secretly leaves.
After the ending credits, Akitoki met his future wife named Suzaku. Due to her name's association with Suzaku, one of the four ninja yōkai, he then asked her to change her name to Kagome, thus explaining why Kagome's name is on the Hōjō family tree.