Koyo Yamamoto joined Diamond in 2018 as a new graduate. After working in the Bookstore Marketing Department, he became a writer for Diamond Weekly and Diamond Online in 2019. He mainly covers the retail and service industries, reporting on a wide range of businesses, including trading companies, food and beverages, restaurants, daily necessities, cosmetics, and travel. He enjoys boxercise and mist saunas. Inquiries and messages from whistleblowers are accepted via direct message to his Twitter account (@koyoydiamond).
