The song was first uploaded on January 13, 2009, and is one of Suzuki-P's biggest hits. Achieving over 200,000 views; it was Suzuki-P's first work to have reach Nico Hall of Fame (100,000 views). This song is unique because the lyrics of the song is a combination of different poems written by a poet "Haruo Sato".
It tells of two people (Rin and Len) who were once lovers; though for one odd reason the man had either forgotten or not recognize his love after leaving for a trip. Shocked of not being remembered the woman asked "siGrE" to tell that she can't sleep thinking about him.
As time passed, the woman died; leaving the man with tears. It was then when he realized "the green summer" they once spend together. He then asked "siGrE" to tell that he can't sleep; thinking about her at night, though she was already gone.