Every 4 episodes is a complete story. The time line doesn't change between story lines. The villain in one episode is the hero in the next.
And it always starts the same way, 5 friends from the same school are in a gaming club and then they go to the festival, learn a horrible secret about the town and end up killing each other.
every miniseries starts like this...

and somehow it goes to this...
http://www.youtube.com/watch?v=O8wLU6E8Zsg <--- don't click if you're squeamish
and then back to everyone's happy again... rewind 4 days to before everything went horribly wrong and go down a different story line, and there's always a teaser at the start of every episode segment.
It's damn near addictive. It's like 8 mini movies.