Hi, Alec, and thanks for the question.
That's where it gets a little tricky, actually.
In this particular case, I'd e-mail AnimEigo and ask them if they can point you in the right direction. (In this case, it might be the Japanese rights holder.)
Hope this helps!
Alison L. Roberts - Director of Marketing & Communications, Right Stuf, Inc. (www.rightstuf.com