The episode begins when Sesshomaru cuts a meido into the sky to kill a demon. Totosai says this attack is called the Meido Zangetsuha, which is the true intention of Tenseiga's use. Sesshomaru has not yet mastered this attack, because his meido is a half crescent, but should be a full circle.
Back at Totosai's hideout, InuYasha and Totosai are discussing the demon blade, Dakki. The blade Mujina used was a fake, even though it was made out of one of Ryujin's scales. You have to have one of Ryjin's scales, or it is impossible to construct Dakki. InuYasha wants to find the real Dakki, and defeat it's wielder, to gain it's power in his Tetsusaiga. Totosai says that if InuYasha were to lose, Tetsusaiga would remain a rusty sword forever, because Dakki would absorb all of Tetsusaiga's demonic energy.
Meanwhile, Toshu the swordsmith, is finished constructing the real Dakki. Now the demon Ryujin has come to claim Dakki, the sword Toshu created for him. Toshu is hiding, unwilling to give up the finished Dakki. Ryujin is furious and ready to attack. InuYasha and friends arive, and InuYasha uses his Wind Scar on Ryujin. InuYasha sees Toshu hiding. InuYasha realizes that his Wind Scar is no use against Ryujin, because Ryujin gets his power from his opponent's demonic energy. Kagome, Sango, Miroku, Shippo and Kirara protect Toshu.
A giant demon has slaughtered another wolf demon tribe, and only two young boys remain. The demon injures the older brother. Byakuya, one of Naraku's new incarnations, appears. He spares the boys' lives. Byakuya gives the older, injured boy a Shikon Jewel Shard to heal his wounds.
InuYasha and Ryujin are fighting. InuYasha is using his Wind Scar without effect, InuYasha is persistent, so Ryujin uses the demonic energy he has collected from InuYasha, to attack. This is what InuYasha wanted, so he waits for the attack, and uses the Backlash Wave, which killed Ryujin. Toshu comes and absorbs Ryujin's demonic energy into Dakki. Now Dakki is complete, InuYasha and friends are now uneasy about this new side of Toshu they are beginning to see.
Koga and friends are travelling when the older boy from the slaughtered Wolf Demon Tribe stops them. He has to take Koga's Jewel Shards and bring them to Byakuya by sunset, or his younger brother Shinta will die. It is sunset, the boy runs away, extremely frustrated, with Koga following.
Toshu challenges InuYasha, because he wants Tetsusaiga's demonic energy. InuYasha and Toshu engage in battle, Toshu tells the story of how he created Dakki. The dragon scales are spreading from Dakki to Toshu, soon Dakki will completely consume Toshu.
The young Wolf Demon Tribal boy returns to Byakuya with Koga behind him. Koga uses his Goraishi claws to kill the demon that killed the other Wolf Demon Tribe. Byakuya retreats, but one of his moths takes the boy's younger brother Shinta with him, while spreading huge amounts of demonic energy into the sky. Koga and the boy follow.
Toshu is now covered in scales, having taken InuYasha's demonic energy from his attacks. InuYasha defeatsToshu and gains Dakki's powers, InuYasha's Tetsusaiga is now covered with dragon scales. InuYasha and friends then notice Ginta and Hakkaku running to catch up with Koga, in the direction which Kagome senses four Jewel Shards.
Koga and the boy from the Wolf Demon Tribe meet up with Moryomaru, who now has Shinta. Koga's shards are acting up again, as he attacks Moryomaru. Moryomaru tries to absorb Koga and the boy's Jewel Shards. InuYasha and friends arrive, and Sango saves Shinta, and InuYasha saves Koga and the boy. InuYasha uses the Dragon Scaled Tetsusaiga on Moryomaru. Moryomaru's wound from Sesshomaru has opened up again. Moryomaru fatally hits InuYasha, and retreats. Byakuya appears and says he is impressed by InuYasha's new attack. Byakuya says that he was only there to observe, then he leaves. InuYasha comes to, and wonders what happened to his Tetsusaiga. The scene ends with a shot of the rusty Tetsusaiga.
Byakuya reports back to Naraku, telling him about InuYasha's new Dragon Scaled Tetsusaiga. Naraku wonders which will happen first: InuYasha being consumed by his own sword, or Moryomaru being destroyed by it.
The last thing you see is a shot of Naraku's profile, then the episode ends.