If your Xbox One doesn't automatically pull your 360 save data from the cloud, here's how to force a sync.
(Shamelessly stolen from reddit)
To use your save file from the cloud server-
How to sync you cloud save data from Xbox 360:
- Launch the game
- At title screen, press Back + Menu (aka Start + Select) to open the Xbox 360 menu
- Select Manage Storage (this will end your session, choose YES)
- Choose Saved Games
- Hover over Castlevania HD and press X
- Done!
If it then says the cloud data and the console data don't match, choose the option that says something to the effect of "Last played on another console."
This worked for me. I was so looking forward to playing this again, but was so distressed when my countless hours from the 360 weren't coming over. Hope this saves someone else the momentary heartache.