Shin Bokura no Taiyō: Gyakushū no Sabata

An undetermined amount of time after the events of Boktai 2, main character Django finds himself sealed in an underground prison by Sabata. Sabata, falling to the Dark Matter that corrupts his body, has once again sided with the Immortals, a vampiric race, and wishes to release the Beast of Destruction, Vanargand, with the intent of becoming the Beast itself. Django recovers and then sets out on a quest to stop Sabata and the Immortals once again, whether that means killing Sabata or not.