Ken Hirai (平井 堅, Hirai Ken) is a Japanese singer-songwriter. Since his debut, Hirai has worked as a model, actor, composer, lyricist, singer, and brand ambassador.
During his career, Hirai has released forty-seven singles and eleven studio albums as of January 2024. According to Oricon, his single Hitomi o Tojite (Close Your Eyes) became the best-selling single of 2004 in Japan, while his compilation album Ken Hirai 10th Anniversary Complete Single Collection '95-'05 "Utabaka" became the best-selling album of 2006 in Japan.