Mikio Sakai (酒井ミキオ Sakai Mikio, born August 24, 1970 in Hokkaidō) is a Japanese singer-songwriter. His real name is Mikirō Sakai (酒井幹郎 Sakai Mikirō). He made his debut with the single Ima dake wa Kimi wo Hanasanai (今だけは君を離さない).
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, and Chivalry of a Failed Knight, as well as various other media.