Dopple is one of the three hunters working together with Tzesguerra. He is one of the two who's names are known (the other one being Barry), and the only one who's hatsu is known.
He appears to be a Conjuration type. His hatsu is called "Fly on he Wall: Silent Worker". It's a radar used to determine the whereabouts of other people. He used it to know when Gensuru and his team were incoming.