This story is a sequel to Sonic The Hedgehog x My Little Pony: Make Your Mark - Season 3
One apparently normal day, Dr Eggman tries to steal the Chaos Emeralds from the Crystal Brighthouse, but his attempt fails so badly that he ends up sending the Emeralds to the human world counterpart of Equestria. Now, Sonic sets himself on a mission: to find the Emeralds and bring them back to Equestria before they fall in the wrong hands. But as he travels on this new human world, he also ends up meeting some faces that look very familiar... but are pretty different at the same time.