In the fictional stories featured in the "Death Note" universe, Tsugumi Ohba, the story writer, created characters that lived in a world featuring a notebook in which names written on it would lead to the ones named to die, typically the cause of death being a heart attack when otherwise not specified. Ohba chose names for his characters in a way that, as he described, "seemed real but could not exist in the real world", due to the fact that most of the characters were criminals or victims. Light Yagami, the main character, is depicted as the deadliest of them. Some character details differ between the manga and its anime, live-action film and drama adaptations.