- Both main characters have amnesia.
- Both series contain psychopaths and serial murderers.
- Both series have mystery and thriller elements.
- Both serial killers kill for a particular reason (e.g., in Mouse, the killer murders people who do not sin, while in Psychopath Diary, the murderer kills weak people).
- Both murderers keep a book with information about their killings.

*Psychopath Diary is not as dark as Mouse, but the comedy does not take away from the suspense and thrill.*