"Days"/"Green" is the forty-fourth single by the Japanese singer Ayumi Hamasaki, released on December 17, 2008. In addition to the A-sides "Days" and "Green", the single contains re-recorded versions of Hamasaki's songs "Love: Destiny" and "To Be". The single was Hamasaki's 31st single to reach number one on the Oricon chart and 19th consecutive single to do so.

Ayumi Hamasaki is a Japanese singer, songwriter, record producer, actress, model, spokesperson, and entrepreneur. By 2002, Hamasaki had earned the nickname "Empress of J-pop" due to her popularity in Japan and throughout Asia, as well as being referred to as "the voice of the lost generation". Due to her success and relevance throughout her career, she is considered one of the top solo female artists of the Heisei era for her influence on the music industry and various fashion trends.