The ninjas thought everything would be fine. But they are dead wrong. Something happens and it's not an illness or anything but something to do with Kai especially now that he is a Xania. Please read book 1 first, if not some things may be confusing. #423 - ninjago (22/06/18)

Kai came back from a solo mission to kill the Xania's leader. Xania's were known as the worst enemy anyone could have. They would kill anyone, whether friends or family. They are merciless. Kai was found unconscious and was brought back to the bounty. That was when things started to go not so well... A series of bad events which happens to Kai. #448 - ninjago (09/06/18) #243 - ninjago (22/06/18)

Cole only ever wanted Jay to spend time with him but Jay only cared for Nya. After breaking off their friendship, Cole is suddenly faced with a new mission: to find a new best friend. But as Wu once said, the road you travel is never a straight path and what happens when Cole gets really sick?