Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-96.248.85.55-20140301065930/@comment-24565701-20140301105422

It was highly hinted at that the Nogitsune is all about revenge for being (Apparently) offended in some way. The power of the nemeton just gave him the opportunity to come back, find someone or take possession of people again.

I'm pretty sure its hostility is directed at Kira's family but possibly at the Argents as well.

It is also said though that Nogitsunes just really enjoy a good clusterf*^k and creating chaos just for the hell of it. But like you said, each previous villain had a purpose and this one does as well I'm sure.