Happy! (season 1)

The main hero is Nick Sax, a moody, cynical, wicked drinker and former cop, retires from the service and becomes a killer. Doing his dirty job he is dipping into the world of accident murders, soulless sex and violence. After one case is failed and Sax gets in the hospital a blue unicorn named Happy breaks into his life. He turns out to be an imaginary friend of a little girl who is in trouble and Sax is the only man who can save her. Thanks to that little and constantly positive creature Nick gets a chance at a normal and honest life.