There was once a day where light and darkness existed as two separate entities. Worlds were balanced and things were peaceful. Naturally, those days were not meant to last long. Curiosity caused people to meddle in things they shouldn't. Darkness found its way into the realm of light, destroying worlds in its path.
Those days are over.
Light took control once more and thinks are once again peaceful. However, the peace is not what it seems. Light is no longer the beautiful entity all love to ideal; too much of anything makes it no longer good. It won't be too long until something happens, though it doubtfully will be anything wants.
For the record, I am Oathkeeper Emi on this site. I'm a Global Moderator and I had very little to do with the designing and planning for the site but I help keep things running. If you love Kingdom Hearts and love roleplaying, come give us a look.