User blog comment:Godisme/Enemies in the Dark/@comment-919115-20111116193530/@comment-893506-20111116200939

I sincerely doubt it's something that simple. Usually if Soul Society has wronged someone, they've done so in a significant way. Tosen is an example for that. He felt that the Shinigami and the Central 46 were corrupt because his friend was killed by her husband, and he did not receive what Tosen would think is the proper punishment for someone who recklessly takes the lives of his comrades.

And let's not forget that there are still some things about Soul Society that have not been answered as of yet, and there still might be some aspects of them that we do not know about. Who knows? Maybe Kugo found out the same thing that Aizen did. Maybe he did not. We still do not know, but it seems like (to me anyway) the reason Kugo may have stopped being a Shinigami because he found something out that's unsettling to him. Then again, I could be breathing too much into this, but it seems like a logical reaction: to find something out that's unsettling to a huge degree could spur one into severing ties with that organization.

Either way though, I'm looking forward to what Kugo has to say about this "enemy" he's speaking of.