It’s been four long years since Liquid Ocelot’s tyrannical reign was brought to an end. Characters have moved on and relationships developed. Yet Metal Gear Rising doesn’t really go into MGS4 details.
This story is focused on Raiden alone, and that’s the journey players will take. He has been hired as a contractor for a security firm. The work pays well and he needs work to keep his family life with Rose going. He also happens to be good with a blade, so there’s that.