The song was originally sung by Hinata Haruhana- first uploaded on February 19, 2010, and later on, a Len version was uploaded on March. It's answer song, Nazokake was uploaded a month after Len's version was uploaded, along with Hinata Haruhana's version of it. The song was based on Hinata Haruhana's story Umi ha sono nazotoki wo nozomu noka? (海はその謎解を望むのか?), however, the 'long' version of Nazotoki uploaded on June hinted it was a 'different' version, similar, but not the same. Main article: Nazotoki/Nazokake The song was one of Len Append Power version demo; along with a rearrangement.