Does mirtazapine cause akathisia or relieve it? read it can do both in different people.

Yes: the possibility of mirtazepine causing akathisia is extremely rare. It is much more likely to relieve it. I see you have also been diagnosed with restless legs syndrome which may be difficult to distinguish from the akathisia. I also see you are on klonopin (clonazepam). After being on it for a while you develop tolerance and may experience rebound anxiety between doses which may resemble akathisia