Renga are Japanese poems created collaboratively by two or more poets. Renga are composed using the tanka for of five lines with the first three resembling haiku in following a 5-7-5 syllable-per-line count and the fourth and fifth lines containing seven syllables each.
The first three lines are written by the first poet and the couplet is then added by the next poet. The couplet must link in some way to the triad. The next triad, linking to the couplet but not the preceeding triad, is added by the next poet, and so on.