Which Japanese poem is famous as a perfect pangram using each kana once? The answer is Iroha. The Iroha is a Japanese poem traditionally written in hiragana, and its fame comes from using the kana characters once each, making it a perfect pangram of the Japanese syllabary.
The poem was long attributed to Kūkai, the influential Buddhist priest who founded Shingon Buddhism. Modern scholarship considers that attribution unlikely and places the poem later in the Heian period. Its earliest known record dates to 1079. The verses are also associated with Buddhist ideas about impermanence.
Iroha was more than a literary curiosity: its sequence served as an ordering system, much like A-B-C in English. It appeared in dictionaries, legal documents, theater seating, military designations, train-car classes, and musical note names. The modern gojūon ordering eventually became standard.
A small historical qualification explains why “each kana” is a simplification. The kana ん was not distinguished from む in writing until the early twentieth century, so the poem’s perfect coverage reflects the writing system of its period rather than every modern kana symbol.