Leon, who has succeeded the name of Golden Knight "GARO," devotes himself to train a young Makai Knight for the next generation, together with Prince Alfonso of the Valiante Kingdom. Then, they receive an order to exterminate the most beautiful Horror in the world which resides in a neighboring country "Vazelia." At the same time, a young Makai Knight for the next generation is kidnapped by an unknown person. Leon desperately follows them, only to find that he is surrounded by his enemies at a dead end. Then, a Makai Knight Dario who was supposed to be missing for some time suddenly appears and rescues him. Under his guidance, Leon is led to the town where he meets up a totally unexpected person.
On the day Tōma Kamijō and Index see Academy City's space elevator, Endymion in the distance, they meet a Level 0 girl with an amazing singing voice, Arisa Meigo. As the three enjoy their time together after school, magic-user Stiyl Magnus suddenly attacks them. His target: Arisa. Why would a girl from the science side be targeted by someone from the magic side, Tōma wonders. In the chaos of Stiyl's attack, he tells Tōma, Index and Arisa that she might cause a war between the magic side and the science side.
Lupin is framed for the murder of Inspector Zenigata by a mysterious assailant holding a silver-coloured Walther P38 pistol Lupin himself once owned. Tracking the true killer leads Lupin to the island of the bloodthirsty Tarantula assassins inside the Devil’s Triangle. After joining the spider-tattooed army against their will, Lupin and his gang make both new friends and enemies as they not only plan to take home the Tarantulas’ massive gold repository for themselves, but hunt down the shooter from Lupin’s past. Can Lupin put to rest this demon who haunts his memories with the Walther P38?