"Karatachi no Hana" (Orange Jasmine) is a particularly famous work among Kosaku Yamada's songs, and upon reading the opening line of the poem, "Karatachi no Hana ga saita yo" (The orange jasmine flowers have bloomed), one might naturally find themselves humming the melody. This work was composed in 1925 to a poem by Hakushu Kitahara and dedicated to the soprano singer Ayako Ogino.

Kitahara and Yamada co-founded the magazine "Shi to Ongaku" (Poetry and Music) in 1922, deepening their friendship through the publication of essays on the relationship between poetry and music, as well as song compositions in the magazine. This work was born out of such exchanges.

The trifoliate orange (karatachi) is a shrub of the citrus family with sharp thorns, which bears white flowers in spring, followed by fruits that ripen yellow in autumn. Yamada reportedly felt nostalgia, associating his own childhood days with Kitahara's poem, which expresses emotions with "Karatachi no Hana" as its visual subject.

The poem consists of six stanzas, and Yamada set each word to a melody that sounds as if it's being spoken, generally assigning one character to an eighth note. He changes the time signature to match the melody, a technique also seen in "Kono Michi" (This Road). This allows the melody to be shaped along with the words, achieving what Yamada referred to as the music's "lightness and heaviness". It should be noted that "Karatachi no Hana No. 2," composed using the same poem, is a strophic song.

Later, in 1928, the composer himself arranged it as a piano solo piece, which was dedicated to Kitahara. It adorns the song's melody with arpeggios, possessing a brilliance that contrasts with the sparser texture of the vocal song.