I've been struggling to find a movie for few years now and it's driving me crazy. I watched it every single morning when I was a kid. I'm fifteen now and I watched this in Poland. I'm quite sure it was manga or something.
I remember this little boy with a red string. He always helped everyone or if there was any danger he helped. The intro was like the boy jumped very high and the string that he had slowly changed into a red dragon. I also remember that the boy had a girl friend and she lived under the water or something. I couldn't find anything similar to this what I remember.