In the latest Weekly Famitus (20/12/2012), 7 pages dedicated for Metal Gear Rising Revengeance. They introduced the story line, character relationships, details for all characters including a secret one from MGS4 "Sunny", game techniques and some new never seem weapons carried by Raiden. Check out the full scans here:
Story & Character correlation chart
Secret Character "Sunny" from MGS4
Game techniques and New Raiden weapons!