My mother always told me a story about a man that gained the powers of a god.
No one knows, for sure, what gave him these powers, but many speculations indicate that it was a notebook with the ability to kill.
The man, who became known later as Kira, tried to create a perfect world, free of those who disrupt the natural order of society:
murderers, acquitted but guilty criminals and those who tried to catch him.
Not long after Kira began implementing his plan, a great detective, known only as "L," attempted to dismantle Kira's kingdom.
L posed a huge threat to Kira and his pursuits until, using his intellect and cunning, Kira disposed of L.
However, before Kira could actually make his perfect world manifest, L's successors, known only as Mello and N, followed in their predecessor's suit.
Kira disposed of Mello, but N tricked Kira into revealing himself and, by using his underhanded tactics, killed Kira, his vision of a perfect world yet to be realized.