I rewatched the video recently and I feel like the manga would be better as the opening for this game. Good Guy Vergil is more proactive than regular Dante. So having him in the middle of a case when temen-ni gru rises would be a more interesting open.
The manga never worked as a prequel to me. Changing it to the opening flows better.
Plus following Enzo, Morrison and the other cast members trying to survive the night is a good C-plot.
What happens a year before you ask? Maybe a version of the reboot or first light novel....?
Or something new. I preferred that actually.
Just a thought.