This guide will help you in doing the secret ending in Kitty. The Secret Ending for this Chapter is pretty tough, to be honest. Unlike Previous Chapters, the items for the Secret Ending are mixed around with the items for the Main Ending of the Chapter. 
Keep in mind that the locations of the items are different every round and are not guaranteed to be at the same spot. Also, make sure to not pick up the Green Numbers around the Map for now. 
After Placing the Brown Fruit and the Wire in this Garden, you need to wait for a Tree to Grow up. It is recommended to do other things while this happens. 
Time to check on the tree. 
A Yellow Fruit has dropped from the Green Tree. 
Pick it up and enter the classroom. 
After placing the Fruit on the Table, the Whiteboard will require you to Place a Number. This number might be random for each server. 
Now you can use the Orange Key to progress. 
Use the Top of the Axe with the Handle. 
After getting the Mask, you need to Escape the Chapter normally. 
That’s how you’ll get the Secret Ending. 