From the feature in the Korea Times:
“The Consultant” is not your average thriller. It revolves around a young aspiring novelist who, unbeknownst to himself, becomes part of a hit squad. Upon the requests of his clients, the protagonist conducts elaborate amounts of research and planning in order to make planned murders look natural, creating “reasons” that are convincing enough to make criminalists, investigators and even forensic experts conclude that no criminal activities were involved in the deaths. His crime thriller-like “action plans” are handed over to a hitman, a fellow employee who is unknown to the protagonist, to execute them in return for money from their clients.
Exact 2023 publication date not yet known. The Bookseller suggests the Summer, but Barbara J Zitwer’s website suggests it could be as early as late 2022