This story is a sequel to G5 Adventures in The Smurfs

After a thrilling adventure in New York City, all the ponies want is a nice vacation with their families before they head back on their Unity Quests. But as their vacation is just getting started, they are once again called on another mission where the mortal world and Equestria hangs in the balance.

This time, they join Mystery Incorporated and some new friends in Japan, where the ghost of the Black Samurai races against them to possess an ancient sword, the Sword of Doom, believed to possess incredible powers. But, it'll take not just the ponies and Mystery Inc, but them and their new friends to make sure evil does not threaten their worlds.

In the end, our heroes will learn that loyalty, honor and courage may be their only key to stopping evil and unlocking the answer to the mystery.

(S2E5 of G5 Adventures)