イマジナリーフレンド

noun

imaginary friend

A direct loanword from English, used in the same sense as in English: a friend made up by a child (or sometimes an adult) that exists only in the imagination.

• 子こ供どもの頃ころ、イマジナリーフレンドがいた。

  When I was a child, I had an imaginary friend.