Catalyst is the name of the game that Ping believes she is playing. The exact nature of this game isn't known for sure. Two basic theories exist on the nature of Catalyst:
- It is an actual game that either comes pre-installed on EDS units or a game that was installed by Tsubasa. If this is the case, then most of the conflict that is occuring with Ping would be related to the harmonizing of the game data with 'real world' situations that may closely match game data.
- Catalyst is the name of a game planted exclusively into Ping by Miho. The theory asserts that the 'game' was named after Miho's observation of Piro and Kimiko's relationship and her desire to "play both" of the separate games that, presumably, involve Piro and Largo.