Episode 122

The Power of Banryu: Duel to the Death on Mt. Hakurei is the one hundred twenty-second episode of the InuYasha anime.

Synopsis

 * 1) Bankotsu destroys his thousandth yōkai, giving his Banryū its ultimate power.
 * 2) However, doing so caused Bankotsu's blade to emit a demonic aura, making him susceptible to Inuyasha's Bakuryūha, which Inuyasha uses, finally defeating the leader of the Shichinintai.

Summary
After being sent falling into a chasm by Kagura, Miroku and Sango survive, with Sango sticking her boomerang into the wall and hanging onto Miroku with a rope. At the bottom of the pit they find the remains of worm demons that Naraku has used to regenerate from his previous defeat.

Inuyasha continues his fight with Bankotsu, and during the fight he removes three Jewel Shards from Bankotsu's neck, leaving only two inside him. Inuyasha notices Naraku's demons watching on the sidelines, and tells Bankotsu that they will try to kill whoever wins the fight and that Naraku has been using Bankotsu, since he intends to take all pieces of the Shikon Jewel. Bankotsu says, being a mercenary for warlords he knew Naraku was using him all along, and doesn't care, as he is confident that he can kill Naraku.

Bankotsu grabs Banryu and kills enough of Naraku's demons that he has killed a thousand demons with Banryu (much like he has killed a thousand humans already), increasing Banryu's power and giving it a demonic aura. Ironically, this allows Inuyasha to use the Backlash Wave, destroying Banryu and finally defeating Bankotsu.

The cave they are in starts to turn to flesh, and swallows Bankotsu, Koga, and Inuyasha, while Kagome, Shippo, and Kirara reunite with Miroku and Sango.