On episode 9, we learn a bit about Three's past and the fact that he was a mercenary.
I noticed that in the flashbacks, he dressed differently than the way he dresses in the present time.
In the present time, he seems to be dressed as a priest of some sort. He even carries a Bible to activate his Minimum.
Since he quit being a mercenary because he ended up causing the death of a bunch of orphans, I was wondering if Three became some sort of clergyman.