Katty is a triangle devil wandering somewhere in the network of hell.
One day Katty found an idol from the human world, fell in love and came down to the human world.

Katty always has a sad face and is always crying.

When Katty cries, it sheds transparent tears like a quadrangle hologram.
 
Katty has a triangular horn on its head and a triangular ring above its head.

Katty likes everything about triangles, but hates  circles because they trap Katty.