Knockout gas

Soporil in its gaseous form.

Ace soporil

Soporil in its liquid form used by Ace.

Soporil β (Beta), also simply known as Soporil, is an anesthetic drug sold by Cradle Pharmaceutical. It can be categorized as a sedative, and has both a gaseous and liquid form.

In its gaseous form, it is gaseous at room temperature, similar to nitrous oxide. It takes only a few seconds to spread, and even a small amount is very effective. For these reasons, it found widespread acceptance with the police and military forces in numerous countries. It was an effective crowd-suppressant and room-clearer, and is practical, ethical, and humane. High doses can lead to some side effects, the most notable effect being severe memory loss.

Soporil is one of the staple elements of the series; it serves an important role in all three games.


True end 13

Mandrake in All-ice's coffin.

It was developed in 2021 with the extract of different roots, including the root of a plant of the Mandragora family. The method by which it was made was described as extracting and purifying an alkaloid from a variety of mandrake.

Gentarou Hongou had found the plant in All-ice's coffin, after receiving the Gigantic from Free the Soul. The drug was very successful and transformed Cradle Pharmaceutical from being a fledgling business to a multi-million dollar company.

Second Nonary Game

Ace june soporil 2

Ace suffering from the effects of Soporil.

Akane and Aoi Kurashiki, who invested in Cradle Pharmaceutical before the drug became a success, used it in the form of grenades to kidnap the players for the Second Nonary Game. It is suggested that the Soporil may be responsible for some of Seven's amnesia.[1]

It is used during the game on Snake, to move him down to the coffin in the chapel.

Ace uses it on himself to hide what is behind Door 3 (Ace murdered Nagisa Nijisaki, thinking he was Snake). He claims he found a vial while searching one of the small hospital rooms.

In the Safe Ending, a Soporil grenade is thrown into the chapel room by Aoi to knock Junpei out, as Junpei had failed to save his sister.

During the Syringe Ending in the iOS version, Clover uses Soporil to drown Junpei on D Deck, injecting him with a syringe she took from Ace and pushing him down the stairs into the water.

Nonary Game: Ambidex Edition


The bracelets in the Nonary Game: Ambidex Edition contain Soporil.

In Virtue's Last Reward, Soporil is used in the bracelets the Nonary Game: Ambidex Edition. It can also be found in the Infirmary, along with an injection gun. When a player breaks the rules or reaches 0 or lower BP, they are injected with this before being injected with a deadly muscle relaxant called tubocurarine. This causes their respiratory system to stop functioning, resulting in immediate death. This drug was used to make their deaths as painless as possible.

Sigma Gets Knocked Out

Sigma inhales Soporil gas in his car.

Soporil was also used to kidnap some of the players. Before being placed in one of the AB Rooms, K was given a large dose of Soporil by Akane, causing his subsequent amnesia during the game. In addition, Alice is actually resistant to Soporil as a result of her SOIS training (revealed in Alice END), so a large amount was used while kidnapping her, explaining why Clover was unconscious for longer at the beginning of the Nonary Game.

Finally, Sopril is used by Luna to sedate Quark and Dio using the injection gun in the Infirmary.

Decision Game

Soporil may have been used to abduct the participants of the Mars Mission Test Site and move them to the Underground Shelter.

During the Decision Game, one of the drugs in the bracelets was an anesthetic designed to put the subjects to sleep after a 90 minute interval. It is unknown if this was Soporil or a different drug.


  • Soporil is the street name for promethazine.
  • Promethazine can, in fact, cause slight memory loss in rare cases, but it is unlikely it could cause generalized amnesia by itself.
  • In the Japanese version of the game, Soporil is known as "Mandrain", alluding to the mandrake roots.