This animation appears to be a short-form (3-5 minute) loop-based piece, probably originating from a pixiv fan circle or an animator using Crayon or Retas . The visual style is unmistakable: soft, bouncy, hand-drawn cel-shading that feels nostalgic for 2005-era flash portals.
: Red Akazawa (also responsible for original character design). Director : Hideta Oota.
For those who may not know, "Lo, Re Pako!" is a Japanese manga and anime series created by Miki Aihara. The series revolves around Mizuki-chan, a young girl with a lively and energetic personality.