The Zippertile is an NPC found in Number World. It is located in the southeast corner of Number World's first room, to the right of the door with 0's and 1's in front of it.
Overview
Usually, the Zippertile's appearance is the same as the other wall decorations in Number World, having a smile on its face. If it has a happy appearance, the player is advised to wake up and return repeatedly until it changes. Occasionally, the face will have an unhappy expression with an open mouth. Interacting with it while it is in this state causes it to briefly move its mouth and make a sound.
Zippertile does not react to any effects other than the Knife effect, making it one of the few NPCs that the player must stab to access a new area. In most cases the Cat is enough to move a character out of the way.
When using the Knife on it in this state, it screams and makes a surprised expression, confirming it is "alive" and not just a wall decoration. After this change of expression, it opens its zipper to reveal a hole that gives entry to the The Stairway, where KyuuKyuu-kun can be found. Their mouth then smiles again and oozes a red liquid (presumably blood) that borders the entry hole.
Appearance
The Zippertile is a wall decoration that is similar in appearance to a zipper. It has a blue head with a white and pink "body". It has a white, open mouth on its face while having a black right eye and a pink left eye. Two orange appendages sprout from the sides of its head: a leg from its right and an arm from its left.
After entering the Zippertile after it has been stabbed, art of them can still be seen from the other side. Their left eye is now round instead of rectangular, and they seem to possess a small pink nose.