For those who haven't seen Dragon Ball Z I'll use a spoiler.
Spoiler
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They started it off with Raditz coming and now Goku just came back to life and is heading towards Nappa, Vegeta, Piccolo, Gohan and Krillin on his Nimbus.
I'm kind of confused because it has the same episodes as Dragon Ball Z. Why is it called Kai if it's the same?
Can someone illuminate?