Sgt. Frog Episode 133: Arisa - Hunter of Darkness, Halloween in Chaos!
Episode 133 of 358 of Sgt. Frog, aired October 27, 2006, 25 minutes. Available with English subtitles and dub where released.
Episode summary
It`s Halloween, and everyone is having fun dressing up in costumes to attend a monster-themed party! But then a real alien monster starts stalking Fuyuki... to Momoka`s rage! Source: crunchyroll