In the Omori game you can obtain a number of keys. These keyboard keys are labeled with a capital letter. The letter keys start with A all the way to Z. You can find the E key here.
Omori Location Key F
You can find the Omori F Key chasing Basil Shadow during one of the stories in the game.
Looking for Key G. Find the Omori Key G.
You can find all Omori key locations here.