There is a free files that came with this. It contain the song in the mermaid part (It's pretty good) and some drama and free-talk kind of thing.
http://www.dmm.co.jp/transfer/-/free/=/doujin_free_download=d_076478zero/type=dl
http://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_076478zero/