In both dramas, there is a body swap between a policewoman and a criminal. I would say Room No.9 is darker than Tengoku to Jigoku: Psychona Futari, which is more humorous at times, but still pretty intense and dark.
--> Both involve body switching
--> Psychona futari involves body swap between a police officer and criminal suspect
--> Both have a criminal/shady guy as one of the body swap candidates
--> Psychona futari is swapping between male and female while Dude in Me is between 2 males
