Agent Gabriel is a secondary ally featured in the short story Blackstar., that is part of the Thus Spoke Kishibe Rohan: Short Story Collection.
He is an American Speedwagon Foundation agent who commissions Rohan Kishibe to draw a sketch of Spaghetti Man, hoping that would bring them closer to discovering the identity of the higher dimensional creature controlling Spaghetti Man.
(Source: JoJo's Bizarre Encyclopedia)
Content compiled by AnimeList.moe from publicly available sources.
