Dark Arcanum (冥夢の秘薬, Meimu no Hiyaku) is an elixir that appears in Suikoden V.
Dark Arcanum is a special sleeping drug created by Nether Gate's drug development department. It can be used to knock out a target but in high enough doses can kill.
Unlike regular sleeping drugs, it has no taste or smell, making it easy to mix in a target's food or drink, rendering it undetectable. Medical examination will also prove fruitless as the drug gives the appearance of peaceful sleep.
During the Sacred Games, both Richard and Belcoot were affected by Dark Arcanum. This was one of the first indications that Nether Gate still existed in some form. Following the tournament, Murad was able to formulate a neutralising agent that, when taken prior to ingesting Dark Arcanum, rendered it ineffective.
- Gensosuikoden Kiwami Encyclopedia, page 672