So, Devil May Cry 4 is already out in Japan, and Youtube User Kalelulen already post many videos of the game with a lot of spoilers. Some of them are very interesting. You can see them in the link below.
Be advised, the video below contains spoilers about Dante & Nero.
Update Kalelulen already uploaded the ending of the game, so if you're are very anxious to see it, go to link below now.