The story of Len, who watches over Rin. She was dying and Len was worried about her health condition. Unfortunately, Rin's condition worsened and nothing could've been done about it. When her time finally came, it was revealed later that Len had always wanted to tell her that he loved her; but it was too late.
"soundless voice" is the question song to Hitoshizuku-P's hit song "proof of life", first uploaded on October 19, 2008. soundless voice was quite popular with over half a million views, and a month after it was uploaded, Hitoshizuku-P uploaded an "answer song" to tell Rin's version to the story. This song is Hitoshizuku-P's "P name origin"; in the lyrics of the song, a part of it said "Hitoshizuku"