Catherine Wiki

This achievement is unlocked once you complete the Freedom True Ending.

In order to obtain this ending, your karma meter must be in the middle between Law and Chaos. You must also answer confessional questions in Stage 9 in the following way (the answer to 9-1 doesn't matter):

An easy way to keep your karma at neutral during a second playthrough is to completely ignore all phone texts from Catherine and Katherine. At that point, the major thing that changes your karma is the confessional questions, which you can alternate between Law and Chaos each level. Always keep an eye on the meter, and just adjust your answer accordingly, to get it in the middle.

The Ending article has full details on all ending requirements.