雨夜哉 (thematically linked haiku)。

A friend and I were discussing seasonal haiku the other day, and I came across one I really liked:根心に花を算える雨夜哉

negokoro ni
hana o kazoeru
amayo kana

while sleeping,
counting the (cherry) blossoms—
a rainy night

数えるの漢字が「旧字」という漢字で、今使いません。旧字 kyuuji = old-style kanji no longer in use.

I googled "雨夜哉" to see whether anything else would turn up in the setting of a rainy night (with that phrasing), just for fun, and things did:

ぱしぱちは栗としらるる雨夜哉

pashi-pachi ha
kuri to shiraruru
amayo kana

the pitter-patter—
chestnuts and the well-known
rainy night


身にしみて音聞く花の雨夜哉蓼太

mi ni shimite
oto kiku hana no
amayo kana

the rainy night
when the sound of blossoms
penetrates the body


雛の前かしこまりたる雨夜哉

hina no mae
kashikomaritaru
amayo kana

Humbled by
a young bird
on a rainy night


水鳥のあなた任せの雨夜哉

mizudori no
anata makase no
amayo kana

the rainy night
when you give in to (abandon yourself to)
the water-birds


うき時は蟇の遠音も雨夜哉

ukitoki ha
kama no toone mo
amayo kana

the rainy season—
just the far-off sound of a toad
a rainy night

(Apologies for the many weak spots in my translations.)

This evening on the way to 太鼓 we wondered about the difference between 俳句 (haiku) and 川柳　(senryuu), and (via 携帯様) we learned that (1) senryuu end with an additional 7-7; (2) the tone is different—whereas haiku are about nature, senryuu tend to be comical, satirical, or sardonic, treating the more mundane things in life; and (3) because of this difference, senryuu don't need the formal elements of haiku, like 切地 (kireji, cutting particles) and 季語 (kigo, words that indicate the season in which the haiku is set). 習字の先生 says that haiku date more or less to the Edo period but senryuu go much further back, to Nara.

Here's an amazing database of example haiku (俳句例句), organized by either keywords or grammatical elements. It gets very specific with its categorizations. Some of the material in progress, but it's great for finding haiku by theme.