i☆Ris has reached the 10th anniversary of their debut and is enjoying smooth sailing, but there was a thought that came to the minds of the girls. "What will happen to us in the next 10 years?"
 
On the day of a live concert, a mysterious talking white squirrel suddenly appears from a T-shirt of goods delivered to i☆Ris' dressing room! Suddenly, they are enveloped in a dazzling light, and what spreads out before their eyes is a mysterious world with many big rainbows floating on it. This is Risu Risu Land, a world where you can be anything you want to be!
 
The five of them are enjoying themselves in this fun and wonderful place, fulfilling their dreams, but they realize that there is something "missing" in this world. There is no "song" in this world. Shirorisu asks i☆Ris for help to bring back the "song"....
 
Why did the "song" disappear? Can they bring "Song" back to this world once again? And at the end of this journey, will the girls find what they really want to be?　 
(Source: Crunchyroll News)