InuYasha Episode 142: Untamed Entei and Horrible Hakudoshi
Episode 142 of 167 of InuYasha, aired February 16, 2004, 24 minutes. Available with English subtitles and dub where released.
Episode summary
Naraku's child Hakudoshi kills Rygokoki, takes his weapon and earns the right to ride on the legendry horse demon Entei