Sphinx is a pseudo-terrorist group that is composed of two Members, Twelve and Nine, along with an extra member later in the series; Lisa Mishima. Sphinx is a criminal mastermind group but also a unique terrorist group- as they limited as many casualties as possible. This is demonstrated as when a bomb is planted by Sphinx, Nine and Twelve triggers an alarm in a effort to evacuate all citizens as far from the building, evading from debris and the asphyxiating smoke. Another demonstration is when Nine rescues a sleeping civilian after they planted a bomb. Sphinx was formed in theory, several years later after Nine & Twelve escaped from the institution. The Sphinx was considered pseudo as they never killed anyone, or in fact had the lowest casualties of any terrorist group in human history. They also never made any demands like a regular terrorist group, or had no political or religion beliefs as well. Unfortunately, the Sphinx was demolished when the founders/leaders, both Nine and Twelve, were killed. Lisa, being the last member, did not decided to continue Sphinx as she had no abilities or the willpower to continue their operations.
- Sphinx, specifically Nine threatened to trigger a atomic bomb located in a nuclear power plant. This was therefore an effort to desperately ward off US Forces to withdraw. This unfortunately, caused the US Government to view them as a threat to both Japan and the US's Government, also this hostile relation supported by the events of 9/11. This caused US Forces to fire at Twelve, an intimidation tactic towards Nine. But not-soon after Nine dies by the fatal side effects of the drug.
- Sphinx ceased operations when Nine and Twelve deceased, and Lisa left the group and was never known as a Sphinx member.
- Sphinx's name is inspired from a mythical egyptian creature known as "Sphinx".
- Sphinx's only enemy was the Japanese Government, which was also corrupt. Sphinx's goal is to teach the world how evil and corrupt a Government is by launching a program that deemed fatal to the twenty-three test subjects. Also greatly shortened the life of Nine and Five, however not Twelve. The drug is theoretically fatal to the nervous system, causing a Stroke, or a massive, fatal hemorrhage, causing headaches throughout the years then death. It is unknown how Twelve remains unaffected by the lethal side effects, which may be caused by drug-withdrawal and therefore causing vomiting symptoms.