It did seem a little strange that Inuyasha defeated Ryūkotsusei so easily, but watching further, I found that Ryūkotsusei was still sealed there. So perhaps the one Inuyasha defeated was only a clone? At the very beginning of episode seventy-five, "The Plot of the Leopard Cat Four Heavenly Kings," Sesshomaru passed through Ryūkotsusei's Valley and discovered that Ryūkotsusei was still sealed into the cliff, rather than completely destroyed as he had been in episode fifty-four. It was a little strange, so an explanation online suggested that the Ryūkotsusei who was destroyed was only a clone, while the real Ryūkotsusei remained sealed ><
But in the last chapter, Sesshomaru definitely finished him off completely. He even took the Dragon Bones.
After bringing the Dragon Bones to the Dragon Maiden, Asumi solemnly handed the Dragon Pearl to Han and said, "Please treasure it." Although Dragon Pearls were not particularly precious within the Dragon Race, giving one away often meant giving their trust as well. She hoped Han would take this gesture from the Dragon Race seriously.
"Yes." Han agreed earnestly and carefully tucked the amber-colored orb into her robes. She understood everything the Dragon Maiden had left unsaid. Her own feelings for Kikyo, and the Dragon Maiden's feelings for her-she understood them all. She would treasure those feelings in her heart forever, returning to them time and again.
Yet, for some reason, a faint unease lingered in her heart, as though the worst was about to happen.
Soon after leaving the sea, Han had intended to seek out Kikyo immediately and give her the Dragon Pearl. Whether Kikyo used it or not, Han believed her wisdom would allow her to handle the pearl properly. Of course, she was more likely to refuse it outright... But whatever happened, Han wanted to