The Subterranean Study is a location in Octopath Traveler and the dungeon of Cyrus' Chapter 1. It is a small cavern located under the Royal Academy of Atlasdam in Atlasdam where the scholar, Russell conducts his research.
Some time before the events of the game, Russell sold his house and moved into the Subterranean Study to continue his research. Russell also began stealing tomes from the Royal Library and selling them to pay off his gambling debts. However, his crimes are soon discovered by Cyrus Albright, one of Russell's colleagues, who confronts him in his study. Cyrus defeats Russell and turns him in to the city guards.