Born in Ireland. After graduating from the National University of Ireland, Peter MacMillan moved to the United States and earned a Ph.D. He currently serves as a part-time lecturer at the University of Tokyo, a visiting professor at Sagami Women's University, and a visiting professor at Musashino University. In 2023, he became JICA's first instructor specializing in culture.

He published an English translation of "The Hundred Poems by One Hundred Poets" in 2008, winning translation awards in both Japan and the United States. Other publications include "The Tales of Ise" and "One Hundred Poets, One Poem Each", released by Penguin Books. Japanese publications include "Savoring the Manyoshu in English", "Unraveling the Hundred Poets: Mysteries of Japanese Culture Seen Through Waka", "Classical Literature in English: Adult Education Starting with Waka", and "Shin Hyakunin Isshu: A Transcendental Translation for the Modern Age".

In 2024, he served as the guide for the Hyakunin Isshu on NHK's “100 Minutes to Master a Classic.” He has appeared on numerous other programs. That same year, he received the Minister of Foreign Affairs Commendation. He was also awarded the Order of the Rising Sun, Gold Rays with Rosette in the Autumn Decorations. In 2025, he served as a summoner at the Imperial New Year's Poetry Reading.

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