Episode 1: The forbidden Ninja

(Each book is 1 season). Ninjago is once at trouble when Forito an evil Samurai wants to take over! When they find a pre recorded message where Sensei Wu explains about the forbidden scrolls of the real Purple ninja, the Ninja realise that a new prophecy is to be fulfilled.
(Not everything is Canon)

I don't own Ninjago
This takes place after season 15
"Hey, pint-sized I always knew they sold fun-sized warriors at the Mega Monster Amusement Park"