Raichu has a buddy!
This is a Castlevania ghost, specifically the one used in Symphony of the Night and the second DS game, Portrait of Ruin. I don’t get why they used a different ghost for the first DS game (Dawn of Sorrows) then went back to the SotN one for the second, and then changed it again for the third (Order of Eccelsia)… but that’s what they did.
I couldn’t quite tell you which of the three DS Castlevanias I like the best — they each have their ups and downs in terms of linearity vs. exploration, equipment mechanics, spirit collecting, and so on. This is definitely the best ghost of the three, though. PoR’s ghost was just sort of a pissed-off green blob, and OoE’s was a floating severed horse head — which is cool I guess, but an angry horse spirit doesn’t say “ghost” to me the way a burning skullwraith does. I’m also a little puzzled about how such a massive number of horses happened to die, unless the Transylvanian branch of the Mafia was way huge and working super-double-overtime.