Tanka often have themes similar to haiku, such as nature, and it's interesting to note that there was an official government Office of Poetry which conducted tanka competitions, but I think what makes tanka so special is the way they were used in private. Tanka were revered as THE style of love poem. Young men spent a great deal of time constructing just the right words, and then had to decide just the right form of presentation. He may have tinted bamboo paper a pretty color or scattered the paper with tiny flecks of gold and silver foil before rolling it up with a pretty flower or twig.
It almost goes without saying that the words would have then been written in his most careful calligraphy. If the young lady in question responded to his poem with an encouraging tanka of her own, the relationship would proceed. An exchange of new, personal, and unique poems would be expected to be exchanged throughout the courtship.
Below are a few examples of tanka written by Ono Komachi, still a well-known poet today, although she was born in 834 AD (death date unknown). Read each poem several times to get the full meaning. While they may have been written at completely different times about the author's own experience, I read it as one fictional girl's experience with a young man (I find it interesting that she has initiated the poem exchange). Tanka, as with haiku, could be used as a way to write an entire book.
Notice how the first two or three lines often set up the poem with some kind of image while the last two lines describe some kind of reflection/metaphor on that image (the third line acts as a kind of bridge or turning point to connect the top two and bottom two).
Sent anonymously to a man who had passed in front of the screens of my room
Should the world of love
end in darkness,
without our glimpsing
where the moon's light fills the sky?
Sent to a man who seemed to have changed his mind
Since my heart placed me
on board your drifting ship,
not one day has passed
that I haven't been drenched
in cold waves.
Sent in a letter attached to a rice stalk with an empty seed husk
How sad that I hope
to see you even now,
after my life has emptied itself
like this stalk of grain
into the autumn wind.
What do you think?