CD single released in 2008. This is Ryuichi Sakamoto's last CD single released to the public to date. The title track "koko" is a piano piece that became a TV commercial song for the Japan Post Group, and was reincarnated as "3 bears" with new lyrics on the 2010 collection album "UTAU" (with Taeko Onuki). The third song, "dancing in the sky," is a 1 minute and 10 second song that was made as a TV commercial for the "Renoir + Renoir" exhibition sponsored by Nippon Television Network Corporation. The third track, "dancing in the sky," is a 1 minute and 10 second piano piece created as a TV commercial for the "Renoir + Renoir" exhibition sponsored by NTV.