This developing guide to Onimusha: Way of the Sword has been updated with detailed walkthrough information for its "Hidden Treasure" side quest chain, expanding on the previously reported overview of the game's cosmetic customisation and optional content. The new coverage focuses specifically on how players locate and unlock a series of treasure chests scattered across the game's Kyoto setting, which become available once the "To Live is to Suffer" main quest milestone is reached. This matters for players seeking to fully explore the game's optional content, as the chests are tied to cryptic "Old Drawing" clues rather than straightforward map markers.

Each Hidden Treasure quest is triggered by speaking to a specific non-player character, who then hands over an "Old Drawing" containing visual and textual hints—such as landmarks, pagodas or phrases like "where the Buddhas overlook the flow"—that players must interpret to pinpoint a chest's real-world location. The guide details at least five such quests, describing navigation routes from named Spirit Mirror waypoints (including Kiyomizu-zaka Slope, Yasaka Pagoda and Gojo Street) and noting that players must use Musashi's gauntlet to reveal each chest once found. The article carries a spoiler warning for readers.