Sesshomaru learns from the wise tree-demon, Boku'seno that when Inuyasha transforms into a demon, his demon blood takes full control turning him into a mindless killing machine. Elsewhere, Inuyasha ...

Upon healing her wounds inflicted by Naraku, using Midoriko's soul, Kikyo runs into Inuyasha again and reveals the secret to destroying Naraku. It is the day of the annual Fox Demon Exam at the Demon ...

With any long-running anime series (or any media for that matter), filler episodes become almost inevitable. At worst, these can distract from the main plot, derail characters or be just plain boring.