(This is under a massive construction and require a lot of time and effort to explain everything, maybe.)
Every now and then, GF Kari host a number of events that revolves the daily lives of the students.
As the name says, it involves a particular plot-line in the story in GF Kari.
Further info: Story Events
For example, try: Event:30th Story Event
Aka: "My Hero" as roughly translated in the game. Focused on "hunting" bad guys and strange creatures. Players will be put their endurance to the test in this event.
Further info: Raid Events
For example, try: Event:43rd Raid Event
An event that mainly focused on teamwork, you'll be fighting alongside your fellow club members (or a randomized team of other players if you are not in a club) against another team. Winners will get great prizes which including rare cards.
Further info: Club Cup Events
For other events, you can check some old pages written about them. The mechanics are still very similar, so they should help you until we generalize the guides.
For raid events, try Event:42nd Raid Event.
Similar to Raid Events, but with more competition! Fight along side with your teammates or you fellow club members for the most highest points against the opposing team!
Further Info: Team Raid Events
A newly added event that is focused on teamwork, 4 teams of 10 compete for the ranking.
Further info: Scramble Events.