Ansem studied the Heartless and wrote these notes about them. These are all the locations of the Ansem Reports along with the Ansem Report Text Included.

Ansem Report 5:

Receive from defeating Maleficent in Hollow Bastion.
To study Heartless behavior, I picked one out for observation. It wiggled its antennae and as if sensing a target, headed deep into the castle. In the deepest part of the castle, its antennae began vibrating as if searching for something. Suddenly a strange door appeared. I’d never known of its existence.

It had a large keyhole, but didn’t seem to be locked. So I opened the door. What I saw on the other side mystified me. What was that powerful mass of energy? That night I observed a great meteor shower in the sky. Could it be related to the door that I have opened?

This page contains: Kingdom Hearts Ansem Reports, Ansem Reports, Ansem, KH Report, KH1, defeating Malificent, Hollow Bastion, Maleficent, KH1