Hokuto no Ken Episode 100
Raoh is looking for Yuria, but instead finds Rihaku. The two start to fight, with Rihaku using his Gosha Hasui Ken (Five Chariot Wave Smashing Fist), but is soon defeated by Raoh. Raoh demands for him to reveal where Yuria is, but Kenshiro then arrives, having decided to fight Raoh rather than see Yuria, as he knows he must stop him first. He says that it is time for Raoh to die.
Ken blocks many of Raoh's attacks with one arm, but when he tries to kick him back, Raoh throws him to the floor. Raoh goes to punch Kenshiro's head, but Ken warps around his strike, and Raoh notices that Kenshiro's movements are the same as Toki's. Not fully understanding how he managed to do this, Raoh tries another attack known as Hokuto Goushou Ha (North Star Iron Palm Wave)...
...but this also fails, as Kenshiro seemingly warps right through Raoh and strikes him with a Nanto Suicho Ken technique. Raoh realises that Kenshiro may have mastered the ultimate technique of the Hokuto Shinken style that Ryuken had once told him about, known as Musou Tensei (Nil-Thought Rebirth). Only a man who has experienced much sorrow is said to have been able to master it, and it seems that Kenshiro has managed this. The spirits of other fallen warriors appear, as Raoh knows that even he may not be able to win this fight now.
In the manga...
-The fight between Rihaku and Raoh is much longer in the anime, as the writers decided to give Rihaku his own fighting style (Gosha Hasui Ken) in addition to the traps he set. In the manga, after Raoh gets past the traps, the next time he is seen, he is choking Rihaku.
-When the flashback with Raoh and Ryuken ends, a song begins to play. This song is called "Kareru Daichi", and is sung by Akira Kamiya, Kenshiro's voice actor.