Peace has finally returned to Honnouji Academy, and now that the unique high school has fulfilled its original purpose, it is scheduled to close within a month. However, one final event remains: the graduation ceremony. As each student council member prepares to leave their past behind and focus on their future aspirations, Satsuki Kiryuuin struggles to find her own path, having lost her resolve after finally achieving victory. But just before she is set to deliver her speech to the student body, the ceremony is disrupted by mysterious beings identical to the student council members. As Ryuuko Matoi and the Elite Four prepare for battle once more, they quickly discover that the one pulling the strings is an old enemy who has returned to take revenge.