Miyuchi. I know you're looking for Freud related studies to connect to your Hikikomori study. But using this guy's ideas is quite dangerous since as what you've said he is the most bashed genius in the field os psychology.
If you want, I can give you informations about Alfred Adler whose underlying personality theories are high on social factors. He has his own set of "Safeguarding Tendencies" which is equivalent to Freud's "Defense Mechanisms". And in my opinion, his Withdrawal theory fits well to "hikikomori".
And there's also Carl Jung who made used of the idea,"Introversion".
~uwaaa~
I have to go now since mom wants to got hthe mall.
Will type more about these people later . . . ok. . ..