Originally Posted by dragoon
I understand that's based on the events prior to this - Is that watchable without having seen this or are there story elements in that that build on the knowledge of this one?
As already mentioned, the two series are completely separate. Heck, I would not be surprised if the studio that adapted the second series was told they could ignore the previous adaptation.
In fact, there are events told in both series, but the way those events are told are different. It would be like if one had it so the characters climbed a mountain to find a crystal and the other version had them swim across a river. To give a made up example.
On side note, it's interesting to know the difference between the two series. This series is like a bunch of episodic plots with pre-established characters you're likely supposed to already be familiar with. Crimson S is more story focused and about getting to know everyone.