What are you watching when you are jumping?
The full moon on the night of the fifteenth,
That is what I am watching when I am jumping.
Oasis Heart3's Note:  This song was written a loooong time ago (i.e., over 100 years ago), and its creator is now lost to the ages. No one remembers who they are. :(
This song is a classic Japanese kids song, similar to "Twinkle Twinkle Little Star": all Japanese people should know this song. (^^) Since it's short, the lyrics are usually repeated two or three times, as evidenced in this video(which features a children's choir singing the song).
(from Kiwi Musume) This CD single is a reference to this legend and the Japanese moon viewing festival. The name of the rabbit, "15" (or "Ichi-go"...or "One-Five"), refers to the traditional date on which the festival is held (see the second Wiki link). I'm really surprised that this single (whose other 2 tracks are also related to this festival and legend) came out in May, though, as the moon viewing festival is in September.