In Japanese print tradition, haiku are usually written in one line.
Japanese haiku traditionally appear as a vertical column or as a single horizontal line, rather than being broken into the three lines familiar from many English-language editions. The apparent three-part structure comes from the poem’s three metrical phrases, conventionally counted as 5–7–5 *on*, not necessarily from three separate printed lines.
Haiku developed from the opening stanza of renga, a linked-verse tradition. The opening stanza was called *hokku* and later became an independent form. The writer Masaoka Shiki popularized the term “haiku” in the late nineteenth century, helping establish the modern name for the genre.
English-language publishers commonly use three lines to show the 5–7–5 structure clearly, so readers may assume that three-line formatting is universal. It is not. Japanese authors and publishers may also use other layouts, especially for modern or free-form haiku, but one-line presentation remains the conventional print format in Japanese.