It's three years after the events of the original Battle Royale, and Shuya Nanahara is now an internationally-known terrorist determined to bring down the government. His terrorist group, Wild Seven, stages an attack that levels several buildings in Tokyo on Christmas Day, killing 8000 people. In order for the government to study the benefits of "teamwork", the new students work in pairs, with their collars electronically linked so that if one of them is killed, the other dies as well. They must kill Nanahara in three days - or die.

A set of twins -- one a hard-working student and the other a drifter -- team up with a dropout to unlock the secrets of the universe and to build one of their own.

High School student Miyui Mashio is really struggling. She can't fulfill her dream of becoming an idol and her parents are always fighting. Suddenly, she finds a genie in a bottle and through an accident, finds herself back in 1991. She realizes she is now going to school with her parents. But the problem is, her parents do not seem to get along - so Miyui will never be born! Miyui learns her father is interested in idols and so together with her mother and other girls she forms the idol group AGS16 to make sure her parents will eventually fall in love.