Japanese haikai verses, such as hokku, and later in the 19th Century as haiku, often have a 5-on 7-on 5-on sound count, a bit like our morae units. Even in Japan sometimes the natural rhythm of 17-on via 5, 7, 5 is not there on paper but said in verbally to squeeze into that pattern.
Non-Japanese haikai writers often write haiku to capture the length of the shortness by writing less. I love writing both 'free verse' haiku, but only in English, and 575 haiku, but again only in English where our syllables are often much longer.
Two short non-575 Japanese language haiku:
Hosai Ozaki (1885-1926)
Here we have an even shorter haiku:
haiku by Ōhashi Raboku (1890-1933) at 4 Japanese characters.
The Japanese break more haiku rules than the West! :-)
co-founder, Call of the Page
President, United Haiku and Tanka Society