Their student identities are only a cover for their real identities as members of an intelligence organization run by the UN. Their objective is to assassinate other teenagers who have the same abilities.The Flowers have no choice but to complete their missions without fail. Their organization has taken their family members hostage to ensure this. For the Flowers, failure would mean death not only for themselves but also for their loved ones.
This is the story of their struggle against cruel fate, and of how it is human nature to find hope, however bleak the outlook.