• Was chosen the highest ranking color by an Empress around 600 AD; following Chinese example.
• In Japan, made from gromwell dye (むらさぎ）
  • made from the roots
  • roughly the colour of eggplant
  • applying the dye over and over again
  • called こだい　むらさき, purple of old.
  • So popular, that in Heian court いろ without any modifier ment purple.

• Since Heian associated with intimacy:

murasaki no hito-moto yue ni Musashino no
kusa wa mina kara aware to zo miru
(Because of a single clump of gromwell / all the grasses in Musashi Plain are dear to me; anonymous poem from 10th century)

• The association maybe is because the color will rub off, like the bodies and souls are died with thoughts of lovers.

紫の色のゆかりに藤花かかれる松もむつましきかな
murasaki no iro no yukari ni fuji no hana
kakareru matsu mo mutsumashiki kana
(Because of the relationship to the colour purple / the wisteria-hanging pine tree, too, feels intimate; by Fujiwara-no-Akisuke, ~1100 AD)