Kikuo's 12th VOCALOID song, a song about a pair of best friends who has disappeared into (and afterwards from) the sky, having "become a moon and a star". The song features a common theme used by Kikuo, dying together and happily being together forever after death. "Soshite Kimi wa Tsuki ni Natta" is included on the albums EXIT TUNES PRESENTS Supernova 7 and KikuoMiku 2.