Close your eyes... achievement in OMORI

To get this ending, you must be on True Route. Check up on Basil, and you'll engage in a fight. After that, you have to fight Omori. It's impossible to defeat him the first time, so you will lose anyway. When the game gives you an option to continue, press No.

This causes Omori to completely take over Sunny. When he wakes up, follow your Dream World friends to the roof. You then jump off the roof.

You then get the credits, with My Time playing. The screen distorts between the Real World and the Dream World. I don't know why you would get this ending intentionally other than for achievement purposes or you got this accidentally, but I really hope you got the Good Ending after.