Joining Japanese 1 into 2 Chain is very elementary, I've included these instructions simply for a sense of continuity.
Step 1
Bring the two ends of a Japanese 1 into 2 Chain around so that they meet as in the illustration.
If you are trying to make a perfect loop of chain it will be important to try and avoid twists in the chain, this can be very difficult with longer chains.
Step 2
Final Step
Place an open link through the two links coloured copper in the illustration.
Close the open link.
That's all there is to it, you now have a loop of Japanese 1 into 2 Chain