Can someone PLEASE help me remember a cartoon !

Hello, this is strange but hear me out. When i was a kid, somewhere between 1991 to 1994, there was this cartoon i saw once on tv that has stuck with me ever since i seen it, but thing is i cant remember what its called and its REALLY bugging me. Its basically about a flying white horse, from what i can remember, this young boy see's it flying in the sky one day and desperetly trys to chase it, ending up in some kind of tower, running up some creepy stairs with creepy music, i dont think it was a kids cartoon, i remember it being quite dark at times, well at the end the boy meets with the horse, shouts at him for some reason, then hes happy and tells him to'take care for the journey home' sorry but i dont have anything else to remember, it MAY have been an anime, im not sure, but if anyone can help i'd appreciate it !

Emphasis on it not being kiddy but quite dark in some scenes.

CHEEEEERS !

Rick

 

ahh man, i think it was called like rupert or someshit. I remember at the biggining hed ride a flying creature and go into a tower.

 

no, rupert was a cute little bear.