My Japanese friend says it's called the No Name Knot or FZ Knot. He says a lot of the Japanese fishermen use it and especially for tuna fishing. He actually just showed me this today before I saw this post. The bump/knot where the line connects is a lot smaller than any knot I've tied for tying two lines together (usually use uni to uni). He told me that the knot has never failed for him when tied correctly.
-Peter