My Imaginary Life (Imaginary Fiend Asylum X Male Childer Reader)

(Y/N) is a kind boy and lives with his parents that are carrying and nice. When he was young, he had an imaginary name Sillta and They were great friends. They would play games, sleep together and sillta would act like a big sister to y/n. That is until he was taken to the aslyum for his unknown behavior as he can't remember about having one as his parents were worried. He and his imaginary friend will meet new friends and encounter mean staff but while he stays there, something happen as the rumor of ghost of aslyum appear and stalk the kids, but most strangest things are the unkowen forces from beneath the building as something to escape. Can he and others solve the strange place and stop this unkowen force?