Father's old enemy Ryukotsusei

Starts out with Inu walking towards Toutou-sei's as he thinks back on his transformation & he has no clue as to what had happened. We are given flashbacks with Kag narating.

Inu worries he could hurt her. He finds the swordsmith & Inu complains to him.

Meanwhilethe gang is out looking for him. They specuklate as to what he's up to. Kag thinks about how much better it would be for Inu to be on his own right now.

Back to Inu & Toutou-sai. Inu wants to know how to make the Tetsusaiga lighter. He also says he doesn't want to transform again. Then Myouga shows up. Inu's mad at the flea. Since Inu needs to master the sword, Toutou-sai agrees to help him. He tells Inu to kill his fahter's old enemy Ryukotsusei. (that's the dragon Sesshy looks at in the Fukai Mori ending) Inu goes off to find him with Myouga. The dragon demon was sealed by Inu's father who didn't have enough strength to kill him. It was during that fight that lead to his being sealed, that Inutaisho recieves the wounds that killed him.

Meanwhile Naraku has been spying on Inu & gets an idea. He's going to use the dragon demon to destroy Inu.

Inu finally finds the dragon demon. Meanwhile the gang has found Toutou-sai. Kag tells him they are looking for Inu & Toutou-sai finally tells them where he is.

Then back to Inu. Myouga tells him to pierce the demon's heart in the spot where Inutaisho's claw has pinned him to the mountain. Then Naraku shows up.

Back to the gang. Toutou-sai explains that Inu needs to learn on his own how to make the sword lighter. Since he told Toutou-sai he felt badly about killing those people, the swordsmith tells him how to do it.

Meanwhile Naraku has disolved Inutaisho's claw & the dragon demon has awakened. He battles with Inu as Naraku tells him he's the son of the demon who pinned him to the mountain. But the dragon really wants to kill Naraku first. "naraku" is destroyed & Myouga leaves. Then Inu & the dragon battle. It's not as easy as Inu thought it would be. He then winds up dropping the Tetsusaiga as he falls. He starts to transform when the epi ends.