TV anime show I saw like 15 years ago, I think it could be Slayers. I saw this series in Spain (and in Spanish, my mother tongue). Episodes were broadcast one each morning.
I only remember some short scenes.
A child stole something (a small bag, I believe) from the main characters (I think) and ran away among the crowd. This boy could be poorly dressed.
Later on in the same episode, some evil guy has one of the main characters trapped inside ice with some kind of magic and the other(s) go to save her. If I remember correctly, this evil guy is more powerful than they initially think, but this can be just my guess..
Again, if I'm not wrong, the child and the evil guy worked together, the child gave the stolen item to him.
All characters were white, I'd swear the character trapped inside ice was the main feminine character.
The evil guy was a man, more on the thin side, and he was wearing a cape (could be similar to Dr. Strange one, high collared cape)
Definitely, characters don't wear modern clothes nor school uniforms, but I think they have their own custom outfit, similar to nothing