Nightmare

Nightmare opens the Three-Tails filler arc as Team Kakashi, ordered to investigate a lake where the beast stirs, runs into Orochimaru's lingering operations. The episode sets an uneasy tone — a tailed beast with no host, Orochimaru's experiments in the water, and the team still raw from Sasuke's second rejection. Anime-original, but framed as a canon-adjacent mission, it gives the post-reunion cast a threat to face while the manga advances. The lake's monster and the snake's schemes coil together under a darkening sky.