I first saw this puzzle in Nikoli Communication 122, published in 2008. I have given it the preliminary English title “Migration”.
1. Draw arrows representing the movement of some of the letters such that each cluster of cells will contain the same letter. As a result, one cluster will contain every A and no other letter, another will contain every B and no other letter, etc.
2. Paths may not branch, intersect, or cross over letters.