 "Senkō" is the second single to be released by solo artist Tomiko Van after the split up of the Japanese band Do As Infinity.The A-side song was used as the commercial song for the ringtone service site mu-mo, and for music.jp TV-CF.Online store, CD Japan, describes the title song as "a medium tempo track that's just perfect for autumn", and her official website simply describes it as a medium rock number.