The Pokémon anime is officially one of the longest-running animated franchises of all time, and over its five different series - split into 19 seasons - we've seen the lead characters change a little in general appearance.

However, some fans have reacted rather badly the the teaser for the new Sun and Moon anime, based on Pokémon Sun and Moon 3DS title, which is due to air later this year.

The short preview shows Ash returning to school, but it also showcases the new art style, with the lead protagonist boasting a more child-like, comical appearance.

Some fans have reacted rather negatively to the footage, with one YouTuber publishing a video simply entitled "WTF is this" while another comments "Is this fan-made?" - needless to say, we can't be held responsible for any of the potty-mouth action contained with these clips, so watch at your own discretion.

Over on Kotaku, they've highlighted the somewhat rough nature of some of the animation and artwork, which includes a rather strange-looking Pikachu (admittedly screen-grabbed during a piece of fast animation, rather than a static scene):

I don't even

As ever, it's probably wise to reserve judgement until the series is actually on-air, but it's fair to say this marks the biggest visual change in the history of the anime. What are your initial thoughts on the footage? Let us know with a comment.