Aura accumulates Corruption passively over time, measured in ingame days. The default gain is 1 Corruption every 2 days. This can be increased to 1 Corruption every day through a mental change in the Main Chamber.
Using the Star Knightess ability increases Corruption by 4. A mental change in the Main Chamber can increase this by 2. A plot event reduces this number by 1.
Doing H-scenes will always increase Corruption by a set amount per scene (unlike Lewdness, which has a limit for each scene). The Corruption gain is increased on the "pink" version of the scene.
All drugs increase Corruption by 1 when used.
Vice-related actions done in Roya (stealing, blackmail etc.) increase Corruption.
If there is at least one witness for a Vice action, it also increases Infamy.
Killing demons increases Corruption, but also increases the Corruption limit by a larger amount. Note that not all demon fights result in the demon's death.
Certain enemies (e.g. Phantom) will increase Aura's Corruption after or during combat unless certain conditions are met when fighting them.