Wait do I need to beat everyone in proud 或者 critical to unlock the black point? I mean what if 你 beat Terra, Ventus and Aqua in standard mode and the final episode in proud? will that work?

First, 你 need to defeat everyone's story (including the final episode) in standard mode. Then repeat Terra, Ventus, Aqua and Final Episode story but do it in Proud mode. Tried it and I got the blank point.