Mikio Sakai (酒井ミキオ, Sakai Mikio, born August 24, 1970 in Hokkaido) is a Japanese singer-songwriter. His real name is Mikiro Sakai (酒井幹郎, Sakai Mikiro). He made his debut with the single Ima dake wa Kimi wo Hanasanai (今だけは君を離さない, Ima dake wa Kimi wo Hanasanai).

He has composed, written and performed numerous songs for several anime, including Fantastic Children, Tsubasa Chronicle, the Gorō Taniguchi-directed Sunrise productions, Planetes, s-CRY-ed, Code Geass, as well as various other media.