[TOMT] Animated series about a colorful girl hopping around planets.

I was in Korea watching this series on Youtube in 2017. I presume it was a Korean series, since they were speaking that language. It might also be region locked content.

My recollection might be wrong, so bear with me. Basically there was this colorful girl who would travel around gray planets and make them colorful again. The antagonist, if I remember correctly, was a gray girl, "corrupting" the planets with darkness? It was animated in a 2d cartoonish, maybe lineless artstyle. I don't know if there were other characters besides the two.