This takes place after Light and Misa are cleared of being Kira and second Kira. More and more criminals are being killed. None of these killings are happening from Light, Misa, the followers, or the two shinegami (Rem or Ryuk). Light is then kidnapped by the Third Kira.
Mana Kagami is the main antagonist of the movie. She and Laris Kagami are all that are left of Light's good side. Mana's desire is to be one with Light again.
Laris Kagami is one of the antagonists in the movie. He and Mana are all that are left of Light's good side. Laris's desire is to make Mana happy.