Although Kreese declined and Silver listened back then, things have changed. With Kreese locked away in prison, Silver is ready to get what he wants — he’s already taken over the Valley, and now, he’s ready to expand further and take Cobra Kai global with the help of the biggest karate tournament in the world. Ugh, this is not good.
Luckily, Daniel and Johnny intervene and a “Winners Take All” qualifying tournament ensues.
Source: https://www.distractify.com/p/what-is-the-sekai-taikai-karate-tournament