Harvest is a Contractor who had been bonded with and controlled by the Black Dandelion. 

Harvest served in the war of Heaven's Gate in south America 5 years prior to the start of Darker than Black: Shikkoku no Hana. His ability of Matter Degeneration earned him respect, fear and the nickname "The Phantom" during his service. During an attempted assassination of Hei and Bai, Amber appears behind him and stops the assassination attempt. She then tells him that he is weaker than Hei, despite him not being a contractor (at the time) which leads to Harvest harboring a jealous vendetta with Hei. 

Harvest is cold, and cruel, uncaring towards humans and contractors alike. He has Darwinist views, and plots to use the Black Dandelion to turn all humans into contractors, and rid the world of irrational thinking. Ever since his time in South America, he has shown jealously towards Hei due the word Amber and said to him, and actively seeks him out for a personal vendetta, something which Kirihara notes is very unlike a contractor. 

Harvest has the ability to remove the intrinsic field of any object, being living or not by touch. This leaves the object disintegrating, leaving a substance looking similar to sand. Harvest is displayed the ability to avoid bullet wounds by degenerating the bullets before they cause damage. His ability has one known weakness. It can be rendered ineffective while harvest is exposed to an electrical current.

Harvest's price is that he must swallow something round. He has stated that it must be the right roundness and size, being the size of a golf ball. Anything too small apparently won't satisfy the contract and anything too large could make Harvest choke and endanger him. He carries around a bag of what seems like large sweets to satisfy his price.