In the year 2000, a crack opened in the sky, causing monsters to spew forth into the world.
The Earth was luckily saved by winged people from another world wielding the legendary "Panty Cards".
As the crack was never closed, Panty Card was taught to the earthlings to help fend off the monsters.
Now, it's 2020, and Panty Card is a fun card game played all around the world,
and protagonist Santa has just transferred into a famous Panty Card school.