It's an old animated series from either the 70's or early to mid 80's. It was shown on our cable TV, but I cannot find it on the list of shows on TCC...
I am sure the title character was named Blue, in addition to being blue and I remember a line from the title song as "Blue, the future lies (or rests) with you!" I have no idea whether the original language was English, but that was the language of the title song.
I am unsure, but I think the antagonist of the show was named "the warlord" and that Blue was the last man (or one of them).
It has irritated my brother and me for years that we cannot remember the series. Please help :)