Hokuto no Ken Episode 70
Koryu tells Zengyo to find Toki, whilst also telling his sons, Zeus and Aus, to not fight Raoh if he dies. Later on, Raoh finds Koryu waiting for him in a cave, and the two fight. Koryu is determined to seal away Raoh's fists, even using a technique which would end his own life to kill him, known as Shichisei Massatsu (Seven Stars Obliteration).
However this technique fails when Raoh hits Koryu so hard his hands blow off, and he then pummels him with more punches. Koryu dies soon after, whilst Raoh now knows that his wound has fully healed, and he can return as Ken-Oh. As he leaves the cave, he is attacked by Zeus and Aus, but he easily defeats them. However, he does not kill them and tells them not to follow the same paths, as they will share the same fate if they do. Meanwhile, Toki wants to fight Raoh, and decides to prove he is strong enough to do so by fighting Kenshiro.
The two enter a stance known as Hokuto Tenki Shou (North Star Heaven Returning Palm) and fight each other, and the two end up inflicting the same amount of non-fatal injuries on each other. Later on, Toki says he feels that the star of death is burning more brightly and that his time will come soon -so he must fight his brother before it is too late.
In the manga...
-The scene where Koryu tells Zengyo to find Toki and for his sons to not fight Raoh was not in the manga.
-In the manga, the scene where Raoh enters the cave and finds Koryu is where Koryu is first introduced, whilst the anime had him appear earlier. And as a note, this scene in the manga happened right after Raoh left the Holy Cross Mausoleum. There was some filler put in between these two scenes in the anime (see the previous episode).
-Right after when Koryu dies, Toki is shown training in the manga. This is not in the anime.
-Zeus and Aus enter the cave in the manga, and fight Raoh inside it. In the anime, they added a new scene where they set a trap for him when he leaves the cave.
-Zengyo makes his debut in the manga when he appears to tell Toki and Kenshiro that Raoh has returned. In the manga, this character is not a ninja, and is younger. For the anime, they made him older, and decided to make him a ninja for some reason. Also, in the manga, Zengyo specifically states that Koryu has died, whilst in the anime, he does not (as he wouldn't have known yet).
-What Koryu's Shichisei Massatsu was actually meant to do as an attack is unknown, as he drops the stance for it as Raoh goes to hit him.
-A shot from the scene where Ken and Toki fight each other was used for the box art of the Fist of the North Star NES game, released in 1989 by a company called Taxan. Which was great, because the game didn't even feature Toki, and was actually based on the first story arc of Hokuto no Ken 2 (in Japan, the game was called Hokuto no Ken 2, and released two years earlier), an arc that took place several years after the events of this episode.
-This episode marks the last non-flashback appearance of Pel (Lin's puppy). No explanation is given for his sudden absence.