The song was first uploaded on February 5, 2009; making it DATEKEN's 4th work. It's been covered by various utaite, and in various languages (Japanese, Chinese, Korean, English covers). To date, the video has reached over 400,000 views. The song is featured in an EXIT TUNES compilation Vocalogenesis. The song tells of two people (the song is separated to two parts; Rin's part and Len's part, though both are present in the chorus / reff) reminiscing of the past and how they should sing the song of the present; and not looking back to the past.